NOIP2006开心的金明

背包

#include<iostream>#include<cstdio>#include<cmath>#include<algorithm>#include<cstring>#define fo(i,a,b) for(int i=a;i<=b;i++)#define down(i,a,b) for(int i=a;i>=b;i--)using namespace std;#define N 30005#define M 25int w[M],c[M];int f[N];int n,m;int main(){scanf("%d%d",&m,&n);fo(i,1,n){int x,y;scanf("%d%d",&x,&y);w[i]=x;c[i]=x*y;}fo(i,1,n)down(j,m,w[i])f[j]=max(f[j],f[j-w[i]]+c[i]);cout<<f[m]<<endl;return 0;}