【LeetCode】 543. Diameter of Binary Tree 二叉树的直径（Easy）（JAVA）
题目地址: https://leetcode.com/problems/diameter-of-binary-tree/
题目描述：
Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.
Example:
Given a binary tree
1
/ \
2 3
/ \
4 5
Return 3, which is the length of the path [4,2,1,3] or [5,2,1,3].
Note: The length of path between two nodes is represented by the number of edges between them.
题目大意
给定一棵二叉树，你需要计算它的直径长度。一棵二叉树的直径长度是任意两个结点路径长度中的最大值。这条路径可能穿过根结点。
解题方法
任意两个结点路径长度 == 任意节点的左右子树的最长路径
遍历，然后计算，得出所有节点的左右节点的和的最大值
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
int max = 0;
public int diameterOfBinaryTree(TreeNode root) {
height(root);
return max;
}
public int height(TreeNode root) {
if (root == null) return 0;
int left = height(root.left);
int right = height(root.right);
if ((left + right) > max) max = left + right;
return Math.max(left, right) + 1;
}
}
执行用时 : 0 ms, 在所有 Java 提交中击败了 100.00% 的用户
内存消耗 : 39.3 MB, 在所有 Java 提交中击败了 5.08% 的用户
