USACO 2.3.4 Money Systems

注意狀態的定義與轉移

#include <iostream>
#include <fstream>
#include <string>
#define LL long long
//#define LOCAL

using namespace std;

#ifdef LOCAL
ofstream fout ("out.txt");
ifstream fin ("in.txt");
#else
ofstream fout ("money.out");
ifstream fin ("money.in");
#endif

int v[30];
LL dp[10010][30];

int main() {
	int num;
	int sum;
	fin>>num>>sum;

	for (int i = 1; i <= num; ++i)
		fin>>v[i];

	for (int i = 1; i <= num; ++i)
	{
		for (int j = 1; j <= sum; ++j)
		{
		    dp[0][i] = 1;
		    dp[j][i] += dp[j][i-1];
		    if(j>=v[i])
                        dp[j][i] += dp[j-v[i]][i];
		}
	}

	fout<<dp[sum][num]<<endl;
        return 0;
}