二叉树的最大深度

[JesseZhao1990]

答案1

可以利用深度优先遍历和递归的思路

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var maxDepth = function(root) {
    if(root === null) return 0;
    return Math.max(maxDepth(root.left),maxDepth(root.right))+1;
};

答案2

也可以利用广度优先遍历和栈的思路

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var maxDepth = function(root) {
    if(root ===null ) return 0;
    
    var depth = 1
    var stack = [];
    root.depth=1;
    stack.push(root);
    
    while(stack.length>0){
        var node = stack.shift();
        if(node.left){
           depth = node.left.depth = node.depth+1;
           stack.push(node.left) 
        }
        if(node.right){
            depth =  node.right.depth = node.depth+1;
            stack.push(node.right);
        }  
    }
    return depth;
    
};

leetcode原题地址：https://leetcode-cn.com/problems/maximum-depth-of-binary-tree/description/