leetcode 572. Subtree of Another Tree 深度优先遍历DFS

Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node’s descendants. The tree s could also be considered as a subtree of itself.

Example 1:
Given tree s:

 3/ \

4 5
/ \
1 2
Given tree t:
4
/ \
1 2
Return true, because t has the same structure and node values with a subtree of s.
Example 2:
Given tree s:

 3/ \

4 5
/ \
1 2
/
0
Given tree t:
4
/ \
1 2
Return false.

本题题意很简单，直接递归遍历即可

代码如下：

#include <iostream>#include <vector>#include <map>#include <set>#include <queue>#include <stack>#include <string>#include <climits>#include <algorithm>#include <sstream>#include <functional>#include <bitset>#include <numeric>#include <cmath>using namespace std;/*struct TreeNode{     int val;     TreeNode *left;     TreeNode *right;     TreeNode(int x) : val(x), left(NULL), right(NULL) {}};*/class Solution {public:    bool isSubtree(TreeNode* s, TreeNode* t)     {        if (s == NULL)            return false;        else if (isSame(s, t) == true)            return true;        else            return isSubtree(s->left, t) || isSubtree(s->right, t);    }    bool isSame(TreeNode* s, TreeNode* t)    {        if (s == NULL && t == NULL)            return true;        else if (s == NULL && t != NULL || s != NULL && t == NULL)            return false;        else        {            if (s->val != t->val)                return false;            else                return isSame(s->left,t->left) && isSame(s->right,t->right);        }    }};