669. 修剪二叉搜索树 - 力扣（LeetCode）
递归
/*** Definition for a binary tree node.* public class TreeNode {* int val;* TreeNode left;* TreeNode right;* TreeNode() {}* TreeNode(int val) { this.val = val; }* TreeNode(int val, TreeNode left, TreeNode right) {* this.val = val;* this.left = left;* this.right = right;* }* }*/
class Solution {public TreeNode trimBST(TreeNode root, int low, int high) {if(root==null) return root;//递归终止条件if(root.val > high){// 寻找符合区间[low, high]的节点//这里做的就是修剪得工作，把不符合条件得节点抛弃，这里就是把left下面得节点向上抛TreeNode left = trimBST(root.left,low,high);return left;}if(root.val < low){// 寻找符合区间[low, high]的节点TreeNode right = trimBST(root.right,low,high);return right;}root.left = trimBST(root.left,low,high);// root->left接入符合条件的左孩子root.right = trimBST(root.right,low,high);// root->right接入符合条件的右孩子return root;}
}
)
