[bzoj1618][Usaco2008 Nov]购买干草

#include<cmath>
#include<ctime>
#include<queue>
#include<stack>
#include<cstdio>
#include<vector>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define N 105
#define M 50005
#define INF 1000000000 
using namespace std;
int f[N][M],p[N],c[N],n,m;
inline void init(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;++i)
        scanf("%d%d",&p[i],&c[i]);
    for(int i=0;i<=n;++i)
        for(int j=1;j<=m;++j)
            f[i][j]=INF;
    for(int i=1;i<=n;++i){
        for(int j=p[i];j<=m;++j)
            f[i][j]=min(f[i][j],min(f[i-1][j-p[i]],f[i][j-p[i]])+c[i]);
        for(int j=0;j<p[i];++j)
            f[i][m]=min(f[i][m],min(f[i-1][m-j],f[i][m-j])+c[i]);
        for(int j=1;j<=m;++j)
            f[i][j]=min(f[i][j],f[i-1][j]);
    }
    printf("%d\n",f[n][m]);
}
int main(){
    freopen("grass.in","r",stdin);
    freopen("grass.out","w",stdout);
    init();
    fclose(stdin);
    fclose(stdout);
    return 0;
}