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

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.

方法一：

/**

 * Definition for binary tree

 * public class TreeNode {

 *     int val;

 *     TreeNode left;

 *     TreeNode right;

 *     TreeNode(int x) { val = x; }

 * }

 */

public class Solution {

    public boolean isSameTree(TreeNode p, TreeNode q) {

        boolean leftsame=true;

        boolean rifhtsame=true;

        if(p==null&&q==null)

            return true;

        else if((p==null&&q!=null)||q==null&&p!=null)

            return false;

        else if(p.val!=q.val)

            return false;

        leftsame=isSameTree(p.left,q.left);

        rifhtsame=isSameTree(p.right,q.right);

        return leftsame&&rifhtsame;

    }

}