[DP] BZOJ 4247 挂饰

来源：互联网发布：枫树浏览器知乎编辑：程序博客网时间：2024/06/10 03:34

一个01背包

#include<cstdio>#include<cstdlib>#include<algorithm>#include<functional>#include<cstring>using namespace std;typedef pair<int,int> abcd;inline char nc(){static char buf[100000],*p1=buf,*p2=buf;if (p1==p2) { p2=(p1=buf)+fread(buf,1,100000,stdin); return EOF; }return *p1++;}inline void read(int &x){char c=nc(),b=1;for (;!(c>='0' && c<='9');c=nc()) if (c=='-') b=-1;for (x=0;c>='0' && c<='9';x=x*10+c-'0',c=nc()); x*=b;}int n,ans;  abcd s[2500];int f[2][2500];  int main()  {int t;freopen("t.in","r",stdin);freopen("t.out","w",stdout);read(n);for(int i=1;i<=n;i++)  read(s[i].first),read(s[i].second);sort(s+1,s+n+1,greater<abcd>());memset(f,-0x3f,sizeof(f));f[t=0][1]=0;for(int i=1;i<=n;i++,t^=1)for(int j=0;j<=n;j++)  f[t^1][j]=max(f[t][j-s[i].first+1>1?j-s[i].first+1:1]+s[i].second,f[t][j]);  for(int i=0;i<=n;i++)  ans=max(ans,f[t][i]);  printf("%d\n",ans); return 0;}

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