C. Greg and Friends

http://codeforces.com/contest/295/problem/C

简单DP

代码：

#include<iostream>

#include<cstdio>

#include<cstring>

#include<string>

#include<algorithm>

#include<cmath>



#define ll long long

using namespace std;



const int N=55;

const ll MOD = 1000000007;

ll dp[N*4][N][N];

ll c[N][N];

int main()

{

	//freopen("data.in","r",stdin);

	for(int i=0;i<N;++i)

		for(int j=0;j<=i;++j)

		{

			if(i==j||j==0) c[i][j]=1;

			else c[i][j]=(c[i-1][j-1]+c[i-1][j])%MOD;

		}

	int n,m;

	while(cin>>n>>m)

	{

		int a=0;

		int b=0;

		for(int i=1;i<=n;++i)

		{

			int tmp;

			cin>>tmp;

			if(tmp==50)

				++a;

			if(tmp==100)

				++b;

		}

		memset(dp,0,sizeof(dp));

		dp[0][a][b]=1;

		ll ans=-1;

		int i;

		for(i=0;i<n*4;++i)

		{

			for(int l=0;l<=a;++l)

			{

				for(int r=0;r<=b;++r)

				if(dp[i][l][r]>0)

				{//cout<<i<<" "<<l<<" "<<r<<" "<<dp[i][l][r]<<endl;

					if(l==0&&r==0) {ans=dp[i][l][r];break;}

					int l2=((i&1)==0)?l:a-l;

					int r2=((i&1)==0)?r:b-r;

					for(int l1=0;l1<=l2;++l1)

					for(int r1=0;r1<=r2;++r1)

					{

						if(l1+r1==0||(l1*50+r1*100)>m)continue;

						int w=((i&1)==0)?l-l1:l+l1;

						int h=((i&1)==0)?r-r1:r+r1;

						dp[i+1][w][h]=(dp[i+1][w][h]+((c[l2][l1]*c[r2][r1]%MOD)*dp[i][l][r])%MOD)%MOD;

					}



				}

				if(ans!=-1) break;

			}

			if(ans!=-1) break;

		}

		if(ans==-1)

		{cout<<"-1"<<endl;cout<<"0"<<endl;}

		else

		{cout<<i<<endl;cout<<ans<<endl;}

	}



	return 0;

}