力扣 543. 二叉树的直径

🔗 leetcode.cn/problems/di…

题目

• 直径的定义是，任意两个节点之间的最长路径

思路

• 递归

代码

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int diameter;
    int height(TreeNode* node) {
        if (node == nullptr) return 0;
        int l = height(node->left);
        int r = height(node->right);
        int depth = max(l, r) + 1;
        diameter = max(diameter, l + r);
        return depth;
    }

    int diameterOfBinaryTree(TreeNode* root) {
        diameter = 0;
        height(root);
        return diameter;
    }
};