leetCode 100.Same Tree (同树判断) 解题思路和方法

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.
思路：判断两棵树是否相同，很简单，两两比较即可。
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) {
//如果都为空，为真
if(p == null && q == null)
return true;
//如果有一个为空，肯定不相等
if(p == null || q == null)
return false;
//如果值不相等，也肯定不相等
if(p.val != q.val)
return false;
//返回左子树和右子树的结果
return isSameTree(p.left,q.left)&&isSameTree(p.right,q.right);
}
}