Question
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.
Solution
TODO
Code
Here is a sample solution.
/**
* 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) {
calHeight(root);
return max;
}
public int calHeight(TreeNode root) {
if(root == null) return 0;
int l = calHeight(root.left);
int r = calHeight(root.right);
max = Math.max(l+r, max);
return Math.max(l, r) + 1;
}
}
Performance
O(n)