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MaximumDepthBinaryTree.java
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MaximumDepthBinaryTree.java
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package com.leetcode;
import java.util.LinkedList;
import java.util.Queue;
public class MaximumDepthBinaryTree {
//https://leetcode.com/problems/maximum-depth-of-binary-tree/
//Definition for a binary tree node.
public class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode() {}
TreeNode(int val) { this.val = val; }
TreeNode(int val, TreeNode left, TreeNode right) {
this.val = val;
this.left = left;
this.right = right;
}
}
//BFS
class Solution {
public int maxDepth(TreeNode root) {
if(root == null) return 0;
Queue<TreeNode> queue = new LinkedList<>();
queue.offer(root);
int depth = 0;
while(queue.size() > 0){
depth++;
Queue<TreeNode> level = new LinkedList<>();
while(queue.size() >0){
TreeNode node = queue.poll();
if(node.left != null){
level.offer(node.left);
}
if(node.right != null){
level.offer(node.right);
}
}
queue = level;
}
return depth;
}
}
//DFS
class Solution2 {
int max;
public int maxDepth(TreeNode root) {
if(root == null) return 0;
max = Integer.MIN_VALUE;
maxDepthHelper(root,0);
return max;
}
public void maxDepthHelper(TreeNode node,int depth){
if(node == null) return;
if(node.left == null && node.right == null){
max = Math.max(max,depth+1);
return;
}
maxDepthHelper(node.left,depth+1);
maxDepthHelper(node.right,depth+1);
}
}
}