{"id":1127,"date":"2024-10-24T16:58:06","date_gmt":"2024-10-24T08:58:06","guid":{"rendered":"http:\/\/114.55.108.251\/?p=1127"},"modified":"2025-01-14T11:22:40","modified_gmt":"2025-01-14T03:22:40","slug":"leetcode-hot100%e4%ba%8c%e5%8f%89%e6%a0%91","status":"publish","type":"post","link":"https:\/\/guapicoding.com\/?p=1127","title":{"rendered":"LeetCode hot100@\u4e8c\u53c9\u6811"},"content":{"rendered":"\n<p class=\"has-text-align-center wp-block-paragraph\"><em><strong>More content<\/strong><\/em><strong><em>\uff1a<\/em><\/strong><a href=\"https:\/\/guapicoding.com\/?p=1177\" data-type=\"post\" data-id=\"1177\">\u529b\u6263\u9898\u8bb0\u4e4b\u4e8c\u53c9\u6811<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u94fe\u5f0f\u5b58\u50a8\u7684\u4e8c\u53c9\u6811\u8282\u70b9\u5b9a\u4e49\u65b9\u5f0f\uff1a<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>struct TreeNode {\n    int val;\n    TreeNode *left;\n    TreeNode *right;\n    TreeNode(int x) : val(x), left(NULL), right(NULL) {}\n};\n\n<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4e8c\u53c9\u6811\u9012\u5f52\u6c42\u6df1\u5ea6\u7528\u524d\u5e8f\uff0c\u6c42\u9ad8\u5ea6\u7528\u540e\u5e8f<\/li>\n\n\n\n<li>C++\u4e2dmap\u3001set\u3001multimap\uff0cmultiset\u7684\u5e95\u5c42\u5b9e\u73b0\u90fd\u662f\u5e73\u8861\u4e8c\u53c9\u641c\u7d22\u6811\uff0c\u6240\u4ee5map\u3001set\u7684\u589e\u5220\u64cd\u4f5c\u65f6\u95f4\u65f6\u95f4\u590d\u6742\u5ea6\u662flogn\uff0c\u800cunordered_map\u3001unordered_set\uff0c\u5e95\u5c42\u5b9e\u73b0\u662f\u54c8\u5e0c\u8868<\/li>\n\n\n\n<li>257.\u4e8c\u53c9\u6811\u7684\u6240\u6709\u8def\u5f84 + 112. \u8def\u5f84\u603b\u548c = 113. \u8def\u5f84\u603b\u548cii\uff08\u8ddf\u7740\u8d70\u4e00\u904d\uff0c\u5f7b\u5e95\u641e\u61c2\u9012\u5f52\u548c\u56de\u6eaf\uff09<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/binary-tree-inorder-traversal\/\">94. \u4e8c\u53c9\u6811\u7684\u4e2d\u5e8f\u904d\u5386<\/a>\u2705<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>\u9012\u5f52<\/strong><\/em><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\npublic:\n    void traversal(TreeNode *node, vector&lt;int&gt; &amp;v) {\n        if(!node) return ;\n\n        traversal(node-&gt;left, v);\n        v.push_back(node-&gt;val);\n        traversal(node-&gt;right, v);\n    }\n    vector&lt;int&gt; inorderTraversal(TreeNode* root) {\n        vector&lt;int&gt; v;\n        traversal(root, v);\n        \n        return v;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/maximum-depth-of-binary-tree\/\">104. \u4e8c\u53c9\u6811\u7684\u6700\u5927\u6df1\u5ea6<\/a>\u2705<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>Solution1<\/em><\/strong>\uff1a\u9012\u5f52\u904d\u5386\uff0c\u4f7f\u7528\u524d\u5e8f\u6c42\u7684\u662f\u6df1\u5ea6\uff0c\u4f7f\u7528\u540e\u5e8f\u6c42\u7684\u662f\u9ad8\u5ea6 <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4e8c\u53c9\u6811\u8282\u70b9\u7684\u6df1\u5ea6\uff1a\u6307\u4ece<strong>\u6839\u8282\u70b9<\/strong>\u5230<strong>\u8be5\u8282\u70b9<\/strong>\u7684\u6700\u957f\u7b80\u5355\u8def\u5f84\u8fb9\u7684\u6761\u6570\u6216\u8005\u8282\u70b9\u6570\uff08\u53d6\u51b3\u4e8e\u6df1\u5ea6\u4ece0\u5f00\u59cb\u8fd8\u662f\u4ece1\u5f00\u59cb\uff09<\/li>\n\n\n\n<li>\u4e8c\u53c9\u6811\u8282\u70b9\u7684\u9ad8\u5ea6\uff1a\u6307\u4ece<strong>\u8be5\u8282\u70b9<\/strong>\u5230<strong>\u53f6\u5b50\u8282\u70b9<\/strong>\u7684\u6700\u957f\u7b80\u5355\u8def\u5f84\u8fb9\u7684\u6761\u6570\u6216\u8005\u8282\u70b9\u6570\uff08\u53d6\u51b3\u4e8e\u9ad8\u5ea6\u4ece0\u5f00\u59cb\u8fd8\u662f\u4ece1\u5f00\u59cb\uff09<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u672c\u9898\u6c42\u6700\u5927\u6df1\u5ea6\uff0c\u6839\u8282\u70b9\u7684\u9ad8\u5ea6\u5c31\u662f\u4e8c\u53c9\u6811\u7684\u6700\u5927\u6df1\u5ea6\uff0c\u56e0\u6b64\u65e2\u53ef\u4ee5\u4f7f\u7528\u524d\u5e8f\u904d\u5386 \uff0c\u4e5f\u53ef\u4ee5\u4f7f\u7528\u540e\u5e8f\u904d\u5386<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>Solution2<\/em><\/strong>\uff1a\u5c42\u5e8f\u904d\u5386 <\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution1 {\npublic:\n    int traversal(TreeNode *cur) {\n        if(!cur) return 0;\n\n        int l = traversal(cur-&gt;left);\n        int r = traversal(cur-&gt;right);\n        return max(l, r) + 1;\n    }\n    int maxDepth(TreeNode* root) {\n        return traversal(root);\n    }\n};<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution2 {\npublic:\n    int maxDepth(TreeNode* root) {\n        deque&lt;TreeNode*&gt; dq;\n        int res = 0;\n        if(root) dq.push_back(root);\n\n        while(!dq.empty()) {\n            int size = dq.size();\n            res++;\n            while(size--) {\n                TreeNode* cur = dq.front();\n                dq.pop_front();\n                if(cur-&gt;left) dq.push_back(cur-&gt;left);\n                if(cur-&gt;right) dq.push_back(cur-&gt;right);\n            }\n        }\n\n        return res;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/invert-binary-tree\/\">226. \u7ffb\u8f6c\u4e8c\u53c9\u6811<\/a>\u2705<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>\u9012\u5f52\u4e09\u6b65\u8d70<\/em><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>\u7b80\u5355\u7b97\u6cd5\u9898\u4e0d\u7528\u9012\u5f52\u6ca1\u6709\u610f\u4e49 \u953b\u70bc\u9012\u5f52\u601d\u7ef4<\/strong><\/em><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\npublic:\n    void myReverse(TreeNode* cur) {\n        if(!cur) return ;\n        TreeNode *tmp = cur-&gt;left;\n        cur-&gt;left = cur-&gt;right;\n        cur-&gt;right = tmp;\n        myReverse(cur-&gt;left);\n        myReverse(cur-&gt;right);\n    }\n    TreeNode* invertTree(TreeNode* root) {\n        myReverse(root);\n        return root;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/symmetric-tree\/\">101. \u5bf9\u79f0\u4e8c\u53c9\u6811<\/a>\u274c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>\u961f\u5217\u6a21\u62df\u592a\u9ebb\u70e6\u4e86<\/strong><\/em> <em><strong>\u5efa\u8bae\u9012\u5f52<\/strong><\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>\u6ce8\u610f\u5224\u65ad\u903b\u8f91\u600e\u4e48\u6837\u6700\u7b80\uff08\u6bd4\u4ee3\u7801\u968f\u60f3\u5f55\u7b80\u5355\u4e00\u500d\uff09<\/em><\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\npublic:\n    bool digui(TreeNode* left, TreeNode* right) {\n        \/\/\u5de6\u53f3\u8282\u70b9\u90fd\u4e3a\u7a7a \u5bf9\u79f0\n        if(!left &amp;&amp; !right) return true;\n        \/\/\u5de6\u53f3\u8282\u70b9\u53ea\u6709\u4e00\u4e2a\u4e3a\u7a7a \u6216\u8005val\u4e0d\u76f8\u540c \u4e0d\u5bf9\u79f0\n        if(!left || !right || left-&gt;val != right-&gt;val) return false;\n\n        bool f = digui(left-&gt;left, right-&gt;right) &amp;&amp; digui(right-&gt;left, left-&gt;right);\n        return f;\n    }\n    bool isSymmetric(TreeNode* root) {\n        return digui(root-&gt;left, root-&gt;right);\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/diameter-of-binary-tree\/\">543. \u4e8c\u53c9\u6811\u7684\u76f4\u5f84<\/a>\u274c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>\u540e\u5e8f\u904d\u5386\u5c31\u662f\u5929\u7136\u7684\u56de\u6eaf<\/strong><\/em><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\nprivate:\n    int ans;\npublic:\n    int travseral(TreeNode *cur) {\n        if(!cur) return 0;\n   \n        int l = travseral(cur-&gt;left);\n        int r = travseral(cur-&gt;right);\n\n        ans = max(ans, l + r + 1); \/\/\u7ef4\u62a4\u6700\u957f\u76f4\u5f84\n        \n        return max(l, r) + 1; \/\/\u8fd4\u56de\u6700\u5927\u5355\u4fa7\u8def\u5f84\u957f\u5ea6\uff0c\u5f80\u4e0a\u4f20\u9012\n    }\n    int diameterOfBinaryTree(TreeNode* root) {\n        ans = 1;\n        travseral(root);\n     \n        return ans - 1;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/binary-tree-level-order-traversal\/\">102. \u4e8c\u53c9\u6811\u7684\u5c42\u5e8f\u904d\u5386<\/a>\u2705<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>STL\u961f\u5217<\/em><\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\npublic:\n    vector&lt;vector&lt;int&gt;&gt; levelOrder(TreeNode* root) {\n        deque&lt;TreeNode*&gt; dq;\n        vector&lt;vector&lt;int&gt;&gt; res;\n        if(!root) return res;\n        \n        dq.push_back(root);\n        while(!dq.empty()) {\n            int size = dq.size();\n            vector&lt;int&gt; v;\n            while(size--) {\n                TreeNode *cur = dq.front();\n                v.push_back(cur-&gt;val);\n                dq.pop_front();\n                if(cur-&gt;left) dq.push_back(cur-&gt;left);\n                if(cur-&gt;right) dq.push_back(cur-&gt;right);\n            }\n            res.push_back(v);\n        }\n\n        return res;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/convert-sorted-array-to-binary-search-tree\/\">108. \u5c06\u6709\u5e8f\u6570\u7ec4\u8f6c\u6362\u4e3a\u4e8c\u53c9\u641c\u7d22\u6811<\/a>\u274c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>\u9012\u5f52\u53d6\u6570\u7ec4\u4e2d\u95f4\u503c<\/strong><\/em><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\npublic:\n    TreeNode* travseral(vector&lt;int&gt; &amp;nums, int left, int right) {\n        \/\/\u8d2f\u5f7b\u5de6\u95ed\u53f3\u95ed\n        if(left &gt; right) return nullptr;\n\n        int mid = left + (right - left) \/ 2; \/\/\u9632\u6b62\u5f53left\u548cright\u90fd\u662fint\u6700\u5927\u503c\u65f6\u6ea2\u51fa\n        TreeNode *cur = new TreeNode(nums&#91;mid]);\n\n        cur-&gt;left = travseral(nums, left, mid-1);\n        cur-&gt;right = travseral(nums, mid+1, right);\n\n        return cur;\n    }\n    TreeNode* sortedArrayToBST(vector&lt;int&gt;&amp; nums) {\n        TreeNode *root = travseral(nums, 0, nums.size() - 1);\n        \n        return root;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/validate-binary-search-tree\/\">98. \u9a8c\u8bc1\u4e8c\u53c9\u641c\u7d22\u6811<\/a>\u274c\u2705<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>Solution1\uff1a\u4e2d\u5e8f\u904d\u5386\uff0c\u9a8c\u8bc1\u904d\u5386\u7684\u5143\u7d20\u662f\u4e0d\u662f\u4ece\u5c0f\u5230\u5927<\/em><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>Solution2\uff1a\u4e2d\u5e8f\u904d\u5386\u53d6\u51faBST\u7684val\uff0c\u770b\u662f\u5426\u5347\u5e8f<\/em><\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution1 {  \nprivate:\n    TreeNode *pre = nullptr; \/\/\u8bb0\u5f55\u4e0a\u4e00\u4e2a\u8282\u70b9  \npublic:\n    bool isValidBST(TreeNode* cur) {\n        if(!cur) return true;\n\n        bool l = isValidBST(cur-&gt;left);\n\n        if(pre &amp;&amp; pre-&gt;val &gt;= cur-&gt;val) return false;\n        pre = cur;\n\n        bool r = isValidBST(cur-&gt;right);\n\n        return l &amp; r;\n    }\n};<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution2 {  \nprivate:\n    vector&lt;int&gt; v;\n    void traversal(TreeNode* cur) {\n        if(!cur) return;\n\n        traversal(cur-&gt;left); \n        v.push_back(cur-&gt;val);\n        traversal(cur-&gt;right); \n    }\npublic:\n    bool isValidBST(TreeNode* root) {\n        traversal(root);\n        int mmin = v&#91;0];\n        for(int i = 1; i &lt; v.size(); i++) {\n            if(v&#91;i] &lt;= v&#91;i - 1]) return false;\n        }\n        return true;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/kth-smallest-element-in-a-bst\/\">230. \u4e8c\u53c9\u641c\u7d22\u6811\u4e2d\u7b2c K \u5c0f\u7684\u5143\u7d20<\/a>\u2705\u274c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>Solution1\uff1a\u9012\u5f52\u53d6\u51fa\u6240\u6709\u5143\u7d20<\/strong><\/em><strong><em>\uff0c\u6709\u989d\u5916\u7a7a\u95f4\u5f00\u9500<\/em><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>Solution\uff1a<\/em><\/strong><em><strong>\u9012\u5f52\u5229\u7528BST\u7684\u81ea\u8eab\u6027\u8d28<\/strong><\/em><strong><em>\uff0c\u65e0\u989d\u5916\u7a7a\u95f4\u5f00\u9500<\/em><\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution1 {\npublic:\n    void travseral(TreeNode *cur, vector&lt;int&gt; &amp;v) {\n        if(!cur) return ;\n        travseral(cur-&gt;left, v);\n        v.push_back(cur-&gt;val);\n        travseral(cur-&gt;right, v);\n        return ;\n    }\n    int kthSmallest(TreeNode* root, int k) {\n        vector&lt;int&gt; v;\n        travseral(root, v);\n\n        return v&#91;k-1];\n    }\n};<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution2 {\nprivate:\n    int res = 0;\npublic:\n    void travseral(TreeNode *cur, int &amp;k) { \n        \/\/\u6ce8\u610f\u4e0d\u8981\u5fd8\u4e86&amp; \u5426\u5219\u5b50\u9012\u5f52\u4fee\u6539\u7684k\u4e0d\u4f1a\u5f71\u54cd\u7236\u9012\u5f52\n        if(!cur) return ;\n        travseral(cur-&gt;left, k);\n        k--;\n        if(k == 0) {\n            res = cur-&gt;val;\n            return ;\n        }\n        travseral(cur-&gt;right, k);\n    }\n    int kthSmallest(TreeNode* root, int k) {\n        travseral(root, k);\n\n        return res;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/binary-tree-right-side-view\/\">199. \u4e8c\u53c9\u6811\u7684\u53f3\u89c6\u56fe<\/a>\u2705<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>\u7b80\u5355<\/strong><\/em><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\npublic:\n    vector&lt;int&gt; rightSideView(TreeNode* root) {\n        vector&lt;int&gt; res;\n        deque&lt;TreeNode*&gt; dq;\n        \n        if(root) dq.push_back(root);\n        while(!dq.empty()) {\n            int size = dq.size();\n            for(int i = 0; i &lt; size; i++) {\n                TreeNode *cur = dq.front();\n                if(size - 1 == i) res.push_back(cur-&gt;val);\n                dq.pop_front();\n                if(cur-&gt;left) dq.push_back(cur-&gt;left);\n                if(cur-&gt;right) dq.push_back(cur-&gt;right);\n            }\n        }\n\n        return res;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/flatten-binary-tree-to-linked-list\/\">114. \u4e8c\u53c9\u6811\u5c55\u5f00\u4e3a\u94fe\u8868<\/a>\u274c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>\u94bb\u725b\u89d2\u5c16\u4e86\uff0c\u5982\u679c\u60f3\u904d\u5386\u548c\u5c55\u5f00\u540c\u6b65\uff0c\u5c31\u4e0d\u8981\u9012\u5f52<\/em><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>\u76f4\u63a5\u7528\u6700\u66b4\u529b\u7684\u65b9\u6cd5\u5427 \u628a\u8282\u70b9\u90fd\u5b58\u8d77\u6765<\/em><\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\npublic:\n    void travseral(TreeNode* cur, vector&lt;TreeNode*&gt; &amp;v) {\n        if(!cur) return ;\n\n        v.push_back(cur);\n        travseral(cur-&gt;left, v);\n        travseral(cur-&gt;right, v);\n    }\n    void flatten(TreeNode* root) {\n        vector&lt;TreeNode*&gt; v;\n        travseral(root, v);\n\n        TreeNode *dummy = new TreeNode(0);\n        TreeNode *pre = dummy;\n        for(const auto &amp;i : v) {\n            pre-&gt;left = nullptr;\n            pre-&gt;right = i;\n            pre = pre-&gt;right;\n        }\n         \n        root = dummy-&gt;right;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/construct-binary-tree-from-preorder-and-inorder-traversal\/\">105. \u4ece\u524d\u5e8f\u4e0e\u4e2d\u5e8f\u904d\u5386\u5e8f\u5217\u6784\u9020\u4e8c\u53c9\u6811<\/a>\u2705<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>\u540c<\/strong><\/em><a href=\"https:\/\/leetcode.cn\/problems\/construct-binary-tree-from-inorder-and-postorder-traversal\/\"><strong><em>106. \u4ece\u4e2d\u5e8f\u4e0e\u540e\u5e8f\u904d\u5386\u5e8f\u5217\u6784\u9020\u4e8c\u53c9\u6811<\/em><\/strong><\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">link\uff1a<a href=\"http:\/\/114.55.108.251\/?p=1177\" data-type=\"post\" data-id=\"1177\">\u529b\u6263\u9898\u8bb0\u4e4b\u4e8c\u53c9\u6811<\/a><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {<br>public:<br>    TreeNode* travseral(vector&lt;int&gt;&amp; preorder, int preorderBegin, int preorderEnd, vector&lt;int&gt;&amp; inorder, int inorderBegin, int inorderEnd) {<br>        if(inorderEnd == inorderBegin) return nullptr;<br><br>        int root_val = preorder&#91;preorderBegin];<br>        TreeNode *root = new TreeNode(root_val);<br>        if(inorderEnd == inorderBegin + 1) return root;<br>        <br>        int cutIndex = 0;<br>        for(cutIndex = inorderBegin; cutIndex &lt; inorderEnd; cutIndex++) {<br>            if(inorder&#91;cutIndex] == root_val) break;<br>        }<br><br>        int leftInorderBegin = inorderBegin;<br>        int leftInorderEnd = cutIndex;<br>        int rightInorderBegin = cutIndex + 1;<br>        int rightInorderEnd = inorderEnd;<br><br>        int leftPreorderBegin = preorderBegin + 1;<br>        int leftPreorderEnd = preorderBegin + leftInorderEnd - leftInorderBegin;<br>        int rightPreorderBegin = preorderBegin + leftInorderEnd - leftInorderBegin + 1;<br>        int rightPreorderEnd = preorderEnd;<br><br>        root-&gt;left = travseral(preorder, leftPreorderBegin, leftPreorderEnd, inorder, leftInorderBegin, leftInorderEnd);<br>        root-&gt;right = travseral(preorder, rightPreorderBegin, rightPreorderEnd, inorder, rightInorderBegin, rightInorderEnd);<br><br>        return root;<br>    }<br>    TreeNode* buildTree(vector&lt;int&gt;&amp; preorder, vector&lt;int&gt;&amp; inorder) {<br>        return travseral(preorder, 0, preorder.size(), inorder, 0, inorder.size());<br>    }<br>};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u203b<a href=\"https:\/\/leetcode.cn\/problems\/path-sum-iii\/\">437. \u8def\u5f84\u603b\u548c III<\/a>\u2705<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>\u8def\u5f84\u95ee\u9898\u96c6\u5927\u6210\u8005<\/em><\/strong> <\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>Solution1\uff1a<\/em><\/strong><em><strong>\u7406\u6e05\u601d\u8def \u6ce8\u91ca\u5f88\u8be6\u7ec6<\/strong><\/em> <\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>Solution2\uff1a\u4e0a\u9762\u7684\u5199\u6cd5\u53c2\u8003\u4e86<a href=\"https:\/\/leetcode.cn\/problems\/path-sum\/\">112. \u8def\u5f84\u603b\u548c<\/a>\uff0c\u540e\u6765\u4e00\u601d\u8003\u53d1\u73b0\u628a\u5bfb\u627e\u51fd\u6570\u5199\u6210bool\u7c7b\u578b\u7684\u5b8c\u5168\u6ca1\u5fc5\u8981\u554a\uff0c\u8fd8\u641e\u5f97\u7279\u522b\u590d\u6742<\/em><\/strong><em><strong>\uff0c\u5982\u679c\u60f3\u8981\u66f4\u7b80\u6d01\u5c31\u628a\u4e3b\u51fd\u6570\u548c\u904d\u5386\u51fd\u6570\u5199\u5728\u4e00\u8d77\uff0c\u518d\u628ares\u53d8\u91cf\u5199\u6210\u5168\u5c40\u53d8\u91cf\uff0c\u5c31\u4e0d\u7528\u5728\u6bcf\u4e2a\u51fd\u6570\u91cc\u90fd\u52a0\u4e0a\u5b83\u7684\u5f15\u7528\u53c2\u6570\u4e86\uff08\u53ef\u4ee5\u4f46\u6ca1\u5fc5\u8981\uff0c\u73b0\u5728\u7684\u7ed3\u6784\u601d\u8def\u6bd4\u8f83\u6e05\u6670\uff09<\/strong><\/em><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution1 {\npublic:\n    bool findPath(TreeNode *cur, long long int sum, int &amp;res) {\n        \/\/\u5373\u4f7f\u641c\u5230\u4e86\u8def\u5f84\u4e5f\u4e0d\u8981\u76f4\u63a5\u8fd4\u56de \u7ee7\u7eed\u5f80\u4e0b\u641c \u56e0\u4e3a\u53ef\u80fd\u6709\u5305\u542b\u60c5\u51b5\n        \/\/\u6bd4\u5982\u30101\uff0c-2\u3011\u548c\u30101\uff0c-2\uff0c1\uff0c-1\u3011\u90fd\u6ee1\u8db3\u9898\u610f\n        if(!sum) res++; \n        \/\/ if(!sum) return true;\n        \n\n        if(!cur-&gt;left &amp;&amp; !cur-&gt;right) return false;\n\n        if(cur-&gt;left) {\n            sum -= cur-&gt;left-&gt;val;\n            \/\/\u641c\u5230\u4e5f\u4e0d\u5e94\u8be5\u50cf\u8def\u5f84\u603b\u548c1\u90a3\u6837\u76f4\u63a5\u8fd4\u56de\u4e86\n            \/\/\u56e0\u4e3a\u90a3\u662f\u641c\u51fa\u4e00\u6761\u6765\u5c31\u884c \u8fd9\u91cc\u662f\u8981\u641c\u51fa\u6240\u6709\u8def\u5f84\n            \/\/\u4ee5\u67d0\u4e00\u4e2a\u8282\u70b9\u4e3a\u8d77\u70b9\u7684\u8def\u5f84\u53ef\u80fd\u6709\u591a\u6761\n            if(findPath(cur-&gt;left, sum, res)) {\n                \/\/\u56e0\u4e3a\u5728\u8c03\u7528\u8fc7\u7a0b\u4e2d\u641c\u5230\u4e5f\u4e0d\u4f1a\u8fd4\u56detrue \u56e0\u6b64\u8fd9\u91cc\u5fc5\u5b9a\u8fd4\u56defalse\n            }\n            sum += cur-&gt;left-&gt;val;\n        }\n        if(cur-&gt;right) {\n            sum -= cur-&gt;right-&gt;val;\n            if(findPath(cur-&gt;right, sum, res)) {\n                \/\/\u56e0\u4e3a\u5728\u8c03\u7528\u8fc7\u7a0b\u4e2d\u641c\u5230\u4e5f\u4e0d\u4f1a\u8fd4\u56detrue \u56e0\u6b64\u8fd9\u91cc\u5fc5\u5b9a\u8fd4\u56defalse\n            }\n            sum += cur-&gt;right-&gt;val;\n        }\n        \n        return false;\n    }\n    void travseral(TreeNode *cur, long long int targetSum, int &amp;res) {\n        if(!cur) return ;\n        \/\/\u4ee5\u6bcf\u4e2a\u8282\u70b9\u90fd\u5f53\u6210\u8d77\u59cb\u70b9\u641c\u4e00\u904d\n        \/\/\u6b64\u5224\u65ad\u53ea\u9488\u5bf9cur\u8282\u70b9\u81ea\u5df1\u5c31\u6784\u6210\u4e00\u6761\u8def\u5f84\u7684\u60c5\u51b5\n        \/\/\u6b63\u5e38\u60c5\u51b5\u4e0bres\u589e\u52a0\u662f\u572817\u884c\u5b8c\u6210\u7684 \u56e0\u4e3a\u8c03\u7528findPath\u51fd\u6570\u53ea\u8981\u4e0d\u662f46\u884c\n        \/\/\u7684\u60c5\u51b5\u5c31\u90fd\u6700\u7ec8\u8fd4\u56de41\u884cfalse \u56e0\u6b64\u572850\u884c\u4e0d\u4f1ares++ \u6240\u4ee5\u4e0d\u7528\u62c5\u5fc3res\u91cd\u590d++\n        if(findPath(cur, targetSum - cur-&gt;val, res)) {\n            res++;\n            \/\/ cout &lt;&lt; cur-&gt;val &lt;&lt; endl;\n        }\n        \n        travseral(cur-&gt;left, targetSum, res);\n        travseral(cur-&gt;right, targetSum, res);\n    }\n    int pathSum(TreeNode* root, int targetSum) {\n        int res = 0;\n        if(!root) return 0;\n        targetSum =  (long long int)targetSum; \/\/\u4e0d\u7136\u5904\u7406\u5927\u8d1f\u6570\u65f6\u4f1a\u62a5\u9519\n        travseral(root, targetSum, res);\n\n        return res;\n    }\n};<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution2 {\npublic:\n    void findPath(TreeNode *cur, long int sum, int &amp;res) {\n        \/\/\u5373\u4f7f\u641c\u5230\u4e86\u8def\u5f84\u4e5f\u4e0d\u8981\u76f4\u63a5\u8fd4\u56de \u7ee7\u7eed\u5f80\u4e0b\u641c \u56e0\u4e3a\u53ef\u80fd\u6709\u5305\u542b\u60c5\u51b5\n        \/\/\u6bd4\u5982\u30101\uff0c-2\u3011\u548c\u30101\uff0c-2\uff0c1\uff0c-1\u3011\u90fd\u6ee1\u8db3\u9898\u610f\n        if(!sum) res++;         \n\n        if(!cur-&gt;left &amp;&amp; !cur-&gt;right) return ; \/\/\u5230\u53f6\u5b50\u8282\u70b9\u4e86\u5c31\u7ec8\u6b62\n\n        if(cur-&gt;left) {\n            sum -= cur-&gt;left-&gt;val;\n            findPath(cur-&gt;left, sum, res);       \n            sum += cur-&gt;left-&gt;val; \/\/\u56de\u6eaf\n        }\n        if(cur-&gt;right) {\n            sum -= cur-&gt;right-&gt;val;\n            findPath(cur-&gt;right, sum, res);            \n            sum += cur-&gt;right-&gt;val;\n        }\n        \n        return ;\n    }\n    void travseral(TreeNode *cur, long int targetSum, int &amp;res) {\n        if(!cur) return ;\n\n        findPath(cur, targetSum - cur-&gt;val, res);\n        \n        travseral(cur-&gt;left, targetSum, res);\n        travseral(cur-&gt;right, targetSum, res);\n    }\n    int pathSum(TreeNode* root, int targetSum) {\n        int res = 0;\n        if(!root) return 0;\n        targetSum =  (long int)targetSum; \/\/\u4e0d\u7136\u5904\u7406\u5927\u8d1f\u6570\u65f6\u4f1a\u62a5\u9519\n        travseral(root, targetSum, res);\n\n        return res;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><a href=\"https:\/\/leetcode.cn\/problems\/lowest-common-ancestor-of-a-binary-tree\/\">236. \u4e8c\u53c9\u6811\u7684\u6700\u8fd1\u516c\u5171\u7956\u5148<\/a>\u274c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>\u4ece\u76ee\u6807\u8282\u70b9\u5f00\u59cb\u81ea\u5e95\u5411\u4e0a\u56de\u6eaf\uff08\u53ea\u80fd\u540e\u5e8f\uff09\u4e00\u5c42\u5c42\u4f20\u8fc7\u53bb<\/em><\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\npublic:\n    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {\n        if(!root || root == p || root == q) return root;\n        \/\/\u627e\u67d0\u4e00\u6761\u8def\u5f84\u5c31\u8981\u5728\u9012\u5f52\u4e2d\u53ca\u65f6return\uff0c\u800c\u904d\u5386\u6574\u68f5\u6811\u5c31\u50cf\u4e0b\u9762\u8fd9\u6837\u7528\n        \/\/\u8282\u70b9\u6765\u627f\u63a5\uff0c\u9012\u5f52\u5b8c\u7edf\u4e00\u5904\u7406\u5de6\u53f3\u4e24\u4e2a\u9012\u5f52\uff0c\u5373\u5904\u7406\u540e\u5e8f\u904d\u5386\u7684\u4e2d\u95f4\u8282\u70b9\n        \/\/\u904d\u5386\u6574\u4e2a\u6811\u4e0d\u4ee3\u8868\u8981\u628a\u6bcf\u4e2a\u70b9\u90fd\u5904\u7406 \u6bd4\u5982\u793a\u4f8b\u4e00\u641c\u4e86\u4e09\u4e2a\u70b9\u5c31\u8fd4\u56de\u4e86\n        \/\/\u4f46\u5982\u679cp q\u90fd\u662f\u53f6\u5b50\u8282\u70b9 \u90a3\u5c31\u8981\u641c\u5b8c\u6574\u68f5\u6811\u4e86 \u6bd4\u5982\u4ee3\u7801\u968f\u60f3\u5f55\u7684\u793a\u4f8b\u56fe\n        TreeNode *left = lowestCommonAncestor(root-&gt;left, p, q); \/\/\u5de6\n        TreeNode *right = lowestCommonAncestor(root-&gt;right, p, q); \/\/\u53f3\n        \/\/\u4e2d:\n        \/\/\u8fd9\u91ccreturn\u7684\u5c31\u662f\u5de6\u53f3\u4e24\u68f5\u5b50\u6811\u5404\u4e00\u4e2ap q \u5f53\u4e0b\u7684root\u5c31\u662f\u6700\u8fd1\u516c\u5171\u7956\u5148\n        if(left &amp;&amp; right) return root; \n        \/\/\u8fd9\u91ccreturn\u7684\u5c31\u662f\u5de6\u53f3\u4e24\u68f5\u5b50\u6811\u6700\u591a\u6709\u4e00\u68f5\u641c\u5230\u4e86p\u548cq \u7ee7\u7eed\u5f80\u4e0a\u4f20\u9012\u76f4\u5230\u6839\u8282\u70b9  \n        if(!left &amp;&amp; right) return right;\n        else if(left  &amp;&amp; !right) return left;\n        else return nullptr;\n    }\n};<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u203b<a href=\"https:\/\/leetcode.cn\/problems\/binary-tree-maximum-path-sum\/\">124. \u4e8c\u53c9\u6811\u4e2d\u7684\u6700\u5927\u8def\u5f84\u548c<\/a>\u274c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>\u7c7b\u4f3c<a href=\"https:\/\/leetcode.cn\/problems\/diameter-of-binary-tree\/\">543. \u4e8c\u53c9\u6811\u7684\u76f4\u5f84<\/a><\/strong><\/em><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Solution {\nprivate:\n    int sum;  \npublic:\n    int travseral(TreeNode* cur) {\n        if(!cur) return 0;\n\n        int l = max(0, travseral(cur-&gt;left)); \/\/\u5982\u679c\u4e3a\u8d1f\u503c\u5c31\u89c6\u4e3a0\uff0c\u4e0d\u8d70\u8be5\u8def\u5f84  \n        int r = max(0, travseral(cur-&gt;right));  \n        sum = max(sum, l + r + cur-&gt;val); \/\/\u7ef4\u62a4\u6700\u5927\u8def\u5f84\u548c  \n\n        return max(l, r) + cur-&gt;val; \/\/\u8fd4\u56de\u6700\u5927\u5355\u4fa7\u8def\u5f84\u548c \n    }\n    int maxPathSum(TreeNode* root) {\n        sum = root-&gt;val;\n        travseral(root);\n\n        return sum;\n    }\n};<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>More content\uff1a\u529b\u6263\u9898\u8bb0\u4e4b\u4e8c\u53c9\u6811 \u94fe\u5f0f\u5b58\u50a8\u7684\u4e8c\u53c9\u6811\u8282\u70b9\u5b9a\u4e49\u65b9\u5f0f\uff1a 94. \u4e8c\u53c9\u6811\u7684\u4e2d\u5e8f\u904d\u5386\u2705 \u9012\u5f52  [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[18,48,19],"class_list":["post-1127","post","type-post","status-publish","format-standard","hentry","category-suanfa","tag-leetcode","tag-48","tag-19"],"_links":{"self":[{"href":"https:\/\/guapicoding.com\/index.php?rest_route=\/wp\/v2\/posts\/1127","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/guapicoding.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/guapicoding.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/guapicoding.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/guapicoding.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1127"}],"version-history":[{"count":33,"href":"https:\/\/guapicoding.com\/index.php?rest_route=\/wp\/v2\/posts\/1127\/revisions"}],"predecessor-version":[{"id":2322,"href":"https:\/\/guapicoding.com\/index.php?rest_route=\/wp\/v2\/posts\/1127\/revisions\/2322"}],"wp:attachment":[{"href":"https:\/\/guapicoding.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1127"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/guapicoding.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1127"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/guapicoding.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1127"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}