[BZOJ4247]挂饰(DP)

当最终挂饰集合确定了，一定是先挂挂钩多的在挂挂钩少的。

于是按挂钩从大到小排序，然后就是简单的01背包。

 #include<cstdio>
 #include<algorithm>
 #define rep(i,l,r) for (int i=(l); i<=(r); i++)
 using namespace std;

 const int N=,inf=1e9;
 int f[N][N];
 int n,ans=-inf,v,c;
 struct P{ int v,c; }s[N];
 bool operator <(const P &a,const P &b){ return a.v>b.v; }

 int main(){
     freopen("bzoj4247.in","r",stdin);
     freopen("bzoj4247.out","w",stdout);
     scanf("%d",&n);
     rep(i,,n) scanf("%d%d",&s[i].v,&s[i].c);
     rep(i,,n) f[][i]=f[i][n+]=-inf;
     f[][]=; sort(s+,s+n+);
     rep(i,,n) rep(j,,n) f[i][j]=max(f[i-][max(j-s[i].v,)+]+s[i].c,f[i-][j]);
     rep(i,,n) ans=max(ans,f[n][i]);
     printf("%d\n",ans);
     return ;
 }