LeetCode [543] Diameter of Binary Tree

543. Diameter of Binary Tree

Easy

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.

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/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode() {} * TreeNode(int val) { this.val = val; } * TreeNode(int val, TreeNode left, TreeNode right) { * this.val = val; * this.left = left; * this.right = right; * } * } */ class Solution { int ret = 0; public int diameterOfBinaryTree(TreeNode root) { helper(root); return ret; } int helper(TreeNode node){ if(node==null) return 0; int l = helper(node.left); int r = helper(node.right); // System.out.println(node.val+" "+l+" "+r); ret = Math.max(l+r, ret); return Math.max(l, r) + 1; } }