HDU 5527---Too Rich（贪心+搜索）

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
using namespace std;
int v[12]={0,1,5,10,20,50,100,200,500,1000,2000};
int c[12],sum[12];
int p,ans;
void dfs(int i,int rest,int count)
{
    if(rest<0) return ;
    if(i==0) {
         if(rest==0) ans=max(ans,count);
         return ;
    }
    int tmp=max(0,rest-sum[i-1]);
    int cn=tmp/v[i]+(tmp%v[i]!=0);
    if(cn<=c[i])  dfs(i-1,rest-cn*v[i],count+cn);
    cn++;
    if(cn<=c[i])  dfs(i-1,rest-cn*v[i],count+cn);
}
int main()
{
    ///cout << "Hello world!" << endl;
    int T; cin>>T;
    while(T--)
    {
        scanf("%d",&p);
        for(int i=1;i<=10;i++) scanf("%d",&c[i]);
        sum[0]=0;
        for(int i=1;i<=10;i++) sum[i]=sum[i-1]+v[i]*c[i];
        ans=-1;
        dfs(10,p,0);
        printf("%d\n",ans);
    }
    return 0;
}
///1020 0 0  0 49  1   0   0   0    1     0