codeforces Paying up 题解

找出一个数组中能否凑成一个给定的值。

就是相当于找零问题。使用动态规划法了。

原题：

http://www.codechef.com/problems/MARCHA1/

Example

Input:
5
3 3
1
1
1
5 11
1
2
4
8
16
5 23
1
2
4
8
16
5 13
1
5
5
10
10
20 132
17
6
4
998
254
137
259
153
154
3
28
19
123
542
857
23
687
35
99
999

Output:
Yes
Yes
Yes
No
Yes

 

#include <string>
#include <algorithm>
#include <stdio.h>
#include <iostream>
using namespace std;

namespace{
	static const int ALL_MON = 1000;
}
int Payingup()
{
	int T = 0, n, m; // n, the number of banknotes in your wallet, and m, the amount of money the muggers asked of you. 
	scanf("%d", &T);
	while (T--)
	{
		scanf("%d %d", &n, &m);
		int *A = new int[n];
		for (int i = 0; i < n; i++)
		{
			scanf("%d", &A[i]);
		}
		if (m > ALL_MON)
		{
			puts("No");
			continue;
		}
		int *B[2];
		B[0] = new int[2*m+2];
		memset(B[0], 0, (2*m+2)*sizeof(int));
		B[1] = B[0] + m+1;
		bool id = 0;
		B[0][0] = B[1][0] = 1;
		for (int i = 0; i < n; i++)
		{
			id = !id;
			for (int j = 1; j <= m; j++)
			{
				if (B[!id][j] || j >= A[i] && B[!id][j - A[i]]) 
					B[id][j] = 1;
			}
		}
		if (B[id][m]) puts("Yes");
		else puts("No");
		delete [] A;
		delete [] B[0];
	}
	return 0;
}