(java)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.

思路：本题是比较两棵树是否相同。从跟节点开始比起，如果p数的叶子节点不等于q数的叶子节点，则直接返回false，否则一直网上遍历，考虑进，p，q中有一个的叶子节点为空，而另一个不是空的情况。

代码如下(已通过leetcode)

/**

 * 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) return false;

        else {

            if(p.val!=q.val) return false;

            else return isSameTree(p.left,q.left)&&isSameTree(p.right,q.right);

        }

    }

}