https://leetcode.com/problems/diameter-of-binary-tree/description/
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.
求二叉树中两个节点距离最远的长度。
采用递归。
递归方法体：
- 如果树为空，则返回0
- 获取当前节点左子树的深度；
- 获取当前节点右子树的深度；
- 类变量diameter的值等于diameter和左右子树深度之和的最大值
- 返回左右子树中最大的值，并+1，+1的目的是包含当前节点
class Solution { int diameter; public int diameterOfBinaryTree(TreeNode root) { getDeepth(root); return diameter; } public int getDeepth (TreeNode root) { if(root == null) return 0; int left = getDeepth(root.left); int right = getDeepth(root.right); diameter = Math.max(diameter, left + right); return Math.max(left, right) + 1; } }