NYOJ927 The partial sum problem(深搜DFS)

题目：

The partial sum problem

时间限制： 1000 ms  |  内存限制： 65535 KB

难度： 2

• • 描述

  • One day,Tom’s girlfriend give him an array A which contains N integers and asked him:Can you choose some integers from the N integers and the sum of them is equal to K. 

    • • 输入
      • There are multiple test cases.
        Each test case contains three lines.The first line is an integer N(1≤N≤20),represents the array contains N integers. The second line contains N integers,the ith integer represents A[i](-10^8≤A[i]≤10^8).The third line contains an integer K(-10^8≤K≤10^8).
      • 输出
      • If Tom can choose some integers from the array and their them is K,printf ”Of course,I can!”; other printf ”Sorry,I can’t!”.
      • 样例输入

      • 4
        1 2 4 7
        13
        4
        1 2 4 7
        15
        

      • 样例输出

      • Of course,I can!
        Sorry,I can't!
        

      • 来源
      • 原创
      • 上传者

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代码：

深搜水题，和部分和问题一样，注释就不写了，应该都能水过~

#include <stdio.h>  
#include <string.h>  
#include <math.h>  
#include <stack>  
#include <algorithm>  
#define mem(a,b) memset(a,b,sizeof(a))  
using namespace std;  
int a[1000];
int n,k;
bool dfs(int s,int sum)
{
	if(s==n)return sum==k;
	if(dfs(s+1,sum))return 1;
	if(dfs(s+1,sum+a[s]))return 1;
	return 0;
}
int main()
{
	n=0;
	while(~scanf("%d",&n))
	{
		for (int i = 0; i < n; i++)
			scanf("%d",&a[i]);
		scanf("%d",&k);
		if (dfs(0,0))
			printf("Of course,I can!\n");
		else
			printf("Sorry,I can't!\n");
		
	}
	return 0;
}

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