代码随想录算法训练营第23天

标签：right TreeNode 23 训练营 随想录 E6% return root left

今日刷题3道：669. 修剪二叉搜索树，108.将有序数组转换为二叉搜索树，538.把二叉搜索树转换为累加树。

●  669. 修剪二叉搜索树

题目链接/文章讲解： https://programmercarl.com/0669.%E4%BF%AE%E5%89%AA%E4%BA%8C%E5%8F%89%E6%90%9C%E7%B4%A2%E6%A0%91.html

视频讲解： https://www.bilibili.com/video/BV17P41177ud

class Solution { public:     TreeNode* trimBST(TreeNode* root, int low, int high) {         if(root==nullptr) return nullptr;         if(root->val < low){             TreeNode* right = trimBST(root->right,low,high);             return right;         }         if(root->val > high){             TreeNode* left = trimBST(root->left,low,high);             return left;         }         root->left =trimBST(root->left,low,high);         root->right=trimBST(root->right,low,high);         return root;     } };

●  108.将有序数组转换为二叉搜索树

https://programmercarl.com/0108.%E5%B0%86%E6%9C%89%E5%BA%8F%E6%95%B0%E7%BB%84%E8%BD%AC%E6%8D%A2%E4%B8%BA%E4%BA%8C%E5%8F%89%E6%90%9C%E7%B4%A2%E6%A0%91.html

视频讲解：https://www.bilibili.com/video/BV1uR4y1X7qL

class Solution { private:     TreeNode* traversal(vector<int>& nums, int left, int right){         if(left > right) return nullptr;         int mid = left + (right - left)/2;         TreeNode* root = new TreeNode(nums[mid]);         root->left = traversal(nums,left,mid-1);         root->right = traversal(nums,mid+1,right);         return root;     } public:     TreeNode* sortedArrayToBST(vector<int>& nums) {         TreeNode* root = traversal(nums,0,nums.size()-1);         return root;     } };

●  538.把二叉搜索树转换为累加树

https://programmercarl.com/0538.%E6%8A%8A%E4%BA%8C%E5%8F%89%E6%90%9C%E7%B4%A2%E6%A0%91%E8%BD%AC%E6%8D%A2%E4%B8%BA%E7%B4%AF%E5%8A%A0%E6%A0%91.html

视频讲解：https://www.bilibili.com/video/BV1d44y1f7wP

class Solution { private:     int pre=0;     void traversal(TreeNode* cur){         if(cur==NULL) return;         traversal(cur->right);         cur->val+=pre;         pre = cur->val;         traversal(cur->left);     } public:     TreeNode* convertBST(TreeNode* root) {         pre=0;         traversal(root);         return root;     } };

标签：right,TreeNode,23,训练营,随想录,E6%,return,root,left
From： https://www.cnblogs.com/zzw0612/p/17061118.html