100. Same Tree

100. Same Tree

题目

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

Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:

Input:     1         1
          /        / 
         2   3     2   3

        [1,2,3],   [1,2,3]

Output: true

Example 2:

Input:     1         1
          /           
         2             2

        [1,2],     [1,null,2]

Output: false

Example 3:

Input:     1         1
          /        / 
         2   1     1   2

        [1,2,1],   [1,1,2]

Output: false

解析

class Solution_100 {
public:
	bool isSameTree(TreeNode *p, TreeNode *q) {

		if (!p&&!q)
		{
			return true;
		}
		if (!p&&q)
		{
			return false;
		}
		if (p&&!q)
		{
			return false;
		}
		if (p->val!=q->val)
		{
			return false;
		}

		return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
	}

	//非递归实现时：有NULL节点也入栈或者队列
	// ref：https://leetcode.com/problems/same-tree/discuss/32683
};

100. Same Tree