diff --git a/problems/0098.验证二叉搜索树.md b/problems/0098.验证二叉搜索树.md index eb877abb..e38c5ade 100644 --- a/problems/0098.验证二叉搜索树.md +++ b/problems/0098.验证二叉搜索树.md @@ -377,6 +377,75 @@ func isBST(root *TreeNode, min, max int) bool { } ``` +JavaScript版本 + +> 辅助数组解决 + +```javascript +/** + * Definition for a binary tree node. + * function TreeNode(val, left, right) { + * this.val = (val===undefined ? 0 : val) + * this.left = (left===undefined ? null : left) + * this.right = (right===undefined ? null : right) + * } + */ +/** + * @param {TreeNode} root + * @return {boolean} + */ +var isValidBST = function (root) { + let arr = []; + const buildArr = (root) => { + if (root) { + buildArr(root.left); + arr.push(root.val); + buildArr(root.right); + } + } + buildArr(root); + for (let i = 1; i < arr.length; ++i) { + if (arr[i] <= arr[i - 1]) + return false; + } + return true; +}; +``` + +> 递归中解决 + +```javascript +/** + * Definition for a binary tree node. + * function TreeNode(val, left, right) { + * this.val = (val===undefined ? 0 : val) + * this.left = (left===undefined ? null : left) + * this.right = (right===undefined ? null : right) + * } + */ +/** + * @param {TreeNode} root + * @return {boolean} + */ +let pre = null; +var isValidBST = function (root) { + let pre = null; + const inOrder = (root) => { + if (root === null) + return true; + let left = inOrder(root.left); + + if (pre !== null && pre.val >= root.val) + return false; + pre = root; + + let right = inOrder(root.right); + return left && right; + } + return inOrder(root); +}; +``` + -----------------------