题目描述

给你一棵二叉树的根节点，返回该树的 直径 。
二叉树的 直径 是指树中任意两个节点之间最长路径的 长度 。这条路径可能经过也可能不经过根节点 root 。
两节点之间路径的 长度 由它们之间边数表示。

提示：

树中节点数目在范围 [1, 10000] 内

-100 <= Node.val <= 100

题解

/*** Definition for a binary tree node.* struct TreeNode {*     int val;*     struct TreeNode *left;*     struct TreeNode *right;* };*/
int maxLen(struct TreeNode* root)
{if(root == NULL){return 0; // Base case: return 0 if the current node is NULL}int leftLen;int rightLen;// Calculate the maximum path length of the left subtreeleftLen = maxLen(root->left) + 1;// Calculate the maximum path length of the right subtreerightLen = maxLen(root->right) + 1;// Return the maximum of the left and right path lengthsreturn leftLen > rightLen ? leftLen : rightLen;
}int Traversal(struct TreeNode* root)
{if(root == NULL){return INT_MIN; // Return minimum integer value if the current node is NULL}int diameter = INT_MIN; // Initialize diameter to minimum integer value// Calculate the diameter passing through the current nodediameter = maxLen(root->left) + maxLen(root->right);// Update diameter with the maximum of diameter, left subtree traversal, and right subtree traversaldiameter = fmax(diameter, Traversal(root->left));diameter = fmax(diameter, Traversal(root->right));return diameter; // Return the final diameter value
}int diameterOfBinaryTree(struct TreeNode* root)
{// Post-order traversal to calculate the diameter of the binary treereturn Traversal(root);
}