BZOJ 4247: 挂饰 动态规划

按照挂件数量排序，然后做一个 DP 就好了.

code:

#include <bits/stdc++.h>
#define ll long long
#define N 2003
#define setIO(s) freopen(s".in","r",stdin)
using namespace std;
ll f[N];
struct node {
    int a,b;
}s[N];
bool cmp(node x,node y) {
    return x.a>y.a;
}
int main()
{
    // setIO("input");
    int i,j,n;
    ll ans=0;
    memset(f,-0x3f,sizeof(f)),f[0]=f[1]=0;
    scanf("%d",&n);
    for(i=1;i<=n;++i) {
        scanf("%d%d",&s[i].a,&s[i].b);
    }
    sort(s+1,s+1+n,cmp);
    for(i=1;i<=n;++i) {
        if(s[i].a!=0) {
            for(j=n;j>=1;--j) {
                int v=min(j+s[i].a-1,n);
                f[v]=max(f[v],f[j]+s[i].b);
                ans=max(ans,f[v]);
            }
        }
        else {
            for(j=1;j<=n;++j)  f[j-1]=max(f[j-1],f[j]+s[i].b),ans=max(ans,f[j-1]);
        }
    }
    printf("%lld\n",ans);
    return 0;
}