Leetcode-标签为Tree 543. Diameter of Binary Tree

原题

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.

代码分析

求二叉树的最大周长。依次求出每个节点的最大周长，然后取出最大值。

代码实现

public class Solution {    public int DiameterOfBinaryTree(TreeNode root) {            if (root == null)                return 0;            int max = Math.Max(nodeDiameter(root), DiameterOfBinaryTree(root.left));            return Math.Max(max, DiameterOfBinaryTree(root.right));    }            private int nodeDiameter(TreeNode node)        {            if (node == null)                return 0;            int sum=0;            if (node.left != null)                sum += height(node.left);            if (node.right != null)                sum += height(node.right);            return sum;        }        private int height(TreeNode node)        {            if (node == null)                return 0;            return 1 + Math.Max(height(node.left), height(node.right));        }}