【bzoj1618】【Usaco2008 Nov]】Buying Hay 购买干草

#include<iostream>
#include<algorithm>
#include<stdio.h>
#define maxn (55005)
using namespace std;
int n,m,w[maxn],c[maxn],dp[maxn+500];
int main()
{
scanf("%d%d",&n,&m);
for (int i=1;i<=maxn+400;i++)
dp[i]=9999999;
for (int i=1;i<=n;i++)
scanf("%d%d",&w[i],&c[i]);

dp[0]=0;
for (int i=1;i<=n;i++)
for (int j=0;j<=maxn+400;j++)
{
if (dp[j]!=9999999&&j+w[i]<=maxn+400)
dp[j+w[i]]=min(dp[j+w[i]],dp[j]+c[i]);
}
int ans=9999999;
for (int j=maxn+400;j>=m;j--)
ans=min(ans,dp[j]);
cout<<ans<<endl;
}