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.
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ /* 二叉树的直径:二叉树中从一个结点到另一个节点最长的路径,叫做二叉树的直径 采用分治和递归的思想:根节点为root的二叉树的直径 = Max(左子树直径,右子树直径,左子树的最大深度(不包括根节点)+右子树的最大深度(不包括根节点)+1) */ class Solution { int res ; public int diameterOfBinaryTree(TreeNode root) { res = 0; getDepth(root); return res; } // 此函数是返回树的最大深度 public int getDepth(TreeNode root){ if(root == null){ return 0; } int left = getDepth(root.left); int right = getDepth(root.right); res = Math.max(res, left+right); return Math.max(left, right) + 1; } }