Diameter of Binary Tree Problem & Solution
Given the root of a binary tree, return 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.
The length of a path between two nodes is represented by the number of edges between them.
See the diameter of binary tree problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("max-inline-insns-recursive-auto")
static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
/**
* 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 diameterOfBinaryTree(TreeNode* root) {
int result = 0;
diameterOfBinaryTree(root, result);
return result;
}
private:
int diameterOfBinaryTree(TreeNode* root, int& diameter) {
if (root == nullptr) {
return -1;
}
int left = 1 + diameterOfBinaryTree(root->left, diameter);
int right = 1 + diameterOfBinaryTree(root->right, diameter);
diameter = max(diameter, left + right);
return max(left, right);
}
};