leetcode/code/lc104.java at master · mJackie/leetcode · GitHub

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package code;

import java.util.ArrayDeque;

import java.util.Queue;

* 104. Maximum Depth of Binary Tree

* 题意：二叉树最大深度

* 难度：Easy

* 分类：Tree, Depth-first Search

* 思路：深度优先搜索，递归实现。非递归BFS，相当于层序遍历。

* Tips：

public class lc104 {

public class TreeNode {

int val;

TreeNode left;

TreeNode right;

TreeNode(int x) { val = x; }

}

public int maxDepth(TreeNode root) {

if(root==null) return 0;

return Math.max(maxDepth(root.left),maxDepth(root.right)) + 1;

}

public int maxDepth2(TreeNode root) {

if(root==null) return 0;

Queue<TreeNode> q = new ArrayDeque<>();

q.add(root);

int depth = 0;

while(!q.isEmpty()){

int size = q.size();

while(size > 0){

TreeNode tn = q.remove();

if(tn.left!=null) q.add(tn.left);

if(tn.right!=null) q.add(tn.right);

size--;

}

depth++;

}

return depth;

}

leetcode/code/lc104.java at master · mJackie/leetcode · GitHub

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