lintcodeleetcode由易至难第11题：Same Tree

Problem:

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

Code:

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public boolean isSameTree(TreeNode p, TreeNode q) { if (p == null && q == null){ return true; } if ((p == null && q != null) | (p != null && q == null)){ return false; } return (p.val == q.val) && isSameTree(p.left,q.left) && isSameTree(p.right,q.right); } }

Code2:

public boolean isSameTree(TreeNode p, TreeNode q) { if(p == null && q == null) return true; if(p == null || q == null) return false; //第一个if已经排除掉左右都为true了 if(p.val == q.val) return isSameTree(p.left, q.left) && isSameTree(p.right, q.right); return false; //此处可以省略else }