https://leetcode.com/problems/maximum-depth-of-binary-tree/description/
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.
package go.jacob.day806; import java.util.LinkedList; import java.util.Queue; public class Demo3 { /* * 解法一： * 递归解法，非常简洁 */ public int maxDepth(TreeNode root) { if(root==null) return 0; return 1+Math.max(maxDepth(root.left), maxDepth(root.right)); } /* * 解法二： 使用queue进行层序遍历 */ public int maxDepth_1(TreeNode root) { if (root == null) return 0; Queue<TreeNode> queue = new LinkedList<TreeNode>(); int res = 0; queue.add(root); while (!queue.isEmpty()) { int size = queue.size(); for (int i = 0; i < size; i++) { TreeNode node = queue.poll(); if (node.left != null) queue.add(node.left); if (node.right != null) queue.add(node.right); } res++; } return res; } private class TreeNode { int val; TreeNode left; TreeNode right; TreeNode(int x) { val = x; } } }
