230.二叉搜索树中第k小的元素

230.二叉搜索树中第k小的元素

/**
 * 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
 * @param {number} k
 * @return {number}
 */
var kthSmallest = function(root, k) {
    let stack=[]
    let node=root
    while(node||stack.length){
        while(node){
            stack.push(node)
            node=node.left
        }
        node=stack.pop()
        if(--k==0){
            return node.val
        }
        node=node.right
    }
    return false
};

采用中序遍历 找到第k个值