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题目链接#xff1a;力扣#xff08;LeetCode#xff09;官网 - 全球极客挚爱的技术成长平台
解题思路#xff1a;如果当前结点小于所给区间#xff0c;那该节点及其左子树肯定不符合条件#xff0c;返回其右子树作为上一结点子树#xff1b;反之…669. 修剪二叉搜索树
题目链接力扣LeetCode官网 - 全球极客挚爱的技术成长平台
解题思路如果当前结点小于所给区间那该节点及其左子树肯定不符合条件返回其右子树作为上一结点子树反之亦然。
C
struct TreeNode* trimBST(struct TreeNode* root, int low, int high) {if (root NULL) return NULL;if (root-val low) return trimBST(root-right, low, high);if (root-val high) return trimBST(root-left, low, high);root-left trimBST(root-left, low, high);root-right trimBST(root-right, low, high);return root;
}
java
class Solution {public TreeNode trimBST(TreeNode root, int low, int high) {if (root null) {return null;}if (root.val low) {return trimBST(root.right, low, high);}if (root.val high) {return trimBST(root.left, low, high);}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
题目链接力扣LeetCode官网 - 全球极客挚爱的技术成长平台
解题思路用折半查找法取中间值为根节点
C:
typedef struct TreeNode TreeNode;
struct TreeNode* traversal(int* nums, int left, int right) {if (left right) return NULL;int mid left ((right - left) / 2);TreeNode* root (TreeNode*)malloc(sizeof(TreeNode));root-valnums[mid];root-left traversal(nums, left, mid - 1);root-right traversal(nums, mid 1, right);return root;
}
struct TreeNode* sortedArrayToBST(int* nums, int numsSize) {TreeNode* root traversal(nums, 0, numsSize - 1);return root;
}
java
class Solution {public TreeNode sortedArrayToBST(int[] nums) {return sortedArrayToBST(nums, 0, nums.length);}public TreeNode sortedArrayToBST(int[] nums, int left, int right) {if (left right) {return null;}if (right - left 1) {return new TreeNode(nums[left]);}int mid left (right - left) / 2;TreeNode root new TreeNode(nums[mid]);root.left sortedArrayToBST(nums, left, mid);root.right sortedArrayToBST(nums, mid 1, right);return root;}
}
538.把二叉搜索树转换为累加树
题目链接力扣LeetCode官网 - 全球极客挚爱的技术成长平台
解题思路逆中序遍历
java
class Solution {TreeNode prenull;public TreeNode convertBST(TreeNode root) {if(rootnull) return null;convertBST(root.right);if(pre!null) root.valpre.val;preroot;convertBST(root.left);return root;}
}
