力扣算法 Java 刷题笔记【二叉树篇】hot100（四）二叉树的直径1

文章目录

• 1. 二叉树的直径（中等）

1. 二叉树的直径（中等）

地址: https://leetcode-cn.com/problems/diameter-of-binary-tree/

2022/01/23
做题反思：

/**
 * 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;
 *     }
 * }
 */
class Solution {
    int maxDiameter = 0;
    public int diameterOfBinaryTree(TreeNode root) {
        maxDepth(root);
        return maxDiameter;
    }
    int maxDepth(TreeNode root) {
        if (root == null) {
            return 0;
        }
        int maxLeft = maxDepth(root.left);
        int maxRight = maxDepth(root.right);
        int myDiameter = maxLeft + maxRight;
        maxDiameter = Math.max(maxDiameter, myDiameter);
        return Math.max(maxLeft, maxRight) + 1;
    }
}