LeetCode oj 104. Maximum Depth of Binary Tree(DFS||BFS)

104. Maximum Depth of Binary Tree

 

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Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

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求二叉树的深度

题很水，DFS和BFS都可以

BFS：

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    int count = 0;    public int maxDepth(TreeNode root) {        Queue<TreeNode> q = new LinkedList<TreeNode>();if(root == null)return 0;q.clear();q.add(root);while(!q.isEmpty()){count++;int len = q.size();for(int i=0;i<len;i++){TreeNode t = q.poll();if(t.left != null){q.add(t.left);}if(t.right != null){q.add(t.right);}}}return count;}}

DFS：

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public int maxDepth(TreeNode root) {      if(root == null){return 0;}if(root.left == null && root.right == null){return 1;}int Depth_left = maxDepth(root.left);int Depth_right = maxDepth(root.right);return Math.max(Depth_left,Depth_right) + 1;}}