LeetCode-Same Tree

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.

检查两棵二叉树是否等价。等价的意思是说，首先两棵二叉树必须拥有相同的结构，并且每个对应位置上的节点上的数都相等。

样例

    1             1   / \           / \  2   2   and   2   2 /             /4             4

就是两棵等价的二叉树。

    1             1   / \           / \  2   3   and   2   3 /               \4                 4

就不是等价的。

 

这道题思路很简单，递归检查每个结点的左右子树是否相等即可。

代码如下：

/** * 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;        }else if(p == null || q == null){            return false;        }        if(p.val == q.val){        return isSameTree(p.left,q.left) && isSameTree(p.right,q.right);     }else{         return false;     }    }}