[LeetCode-100]Same Tree(java)

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.

题意：

给出两颗二叉树，判断这两棵树是否相等。

二叉树相等：两棵树的结构相同，且结点值相等。

分析：

使用递归进行求解，先判断当前结点值是否相等平；如果相等就再比较其左右子树，只有当所有的结点都相等才相等。

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