Bzoj 3550 Vacation

http://www.lydsy.com/JudgeOnline/problem.php?id=3550

Test instructions: There are 3N number, you need to select some number, first of all to ensure that any length is n the number of the selection of <=k, and secondly to ensure that the number of the most selected.

Ideas: And this question like http://www.cnblogs.com/qzqzgfy/p/5612261.html

It can be converted into an inequality and then the cost flow is obtained.

1#include <cstdio>2#include <cmath>3#include <iostream>4#include <algorithm>5#include <cstring>6 #defineINF 0x7fffffff7 inttot,go[200005],next[200005],first[200005],flow[200005],cost[200005];8 intdis[200005],vis[200005],op[200005],edge[200005], from[200005],ans,a[200005];9 intn,k,s,t,c[200005];Ten intRead () { One     intt=0, f=1;CharCh=GetChar (); A      while(ch<'0'|| Ch>'9'){if(ch=='-') f=-1; ch=GetChar ();} -      while('0'<=ch&&ch<='9') {t=t*Ten+ch-'0'; ch=GetChar ();} -     returnt*F; the } - voidInsertintXintYintZintl) { -tot++; -go[tot]=y; +next[tot]=First[x]; -first[x]=tot; +flow[tot]=Z; Acost[tot]=l; at } - voidAddintXintYintZintl) { -Insert (x,y,z,l); op[tot]=tot+1; -Insert (Y,x,0,-L); op[tot]=tot-1; - } - BOOLSPFA () { in     for(inti=s;i<=t;i++) dis[i]=0x3f3f3f3f, vis[i]=0; -    intH=1, t=1; vis[s]=1; c[1]=s;dis[s]=0; to     while(h<=t) { +        intnow=c[h++]; -         for(intI=first[now];i;i=Next[i]) { the              intPur=Go[i]; *              if(dis[pur]>dis[now]+cost[i]&&Flow[i]) { $dis[pur]=dis[now]+Cost[i];Panax Notoginseng                  from[pur]=Now ; -edge[pur]=i; the                 if(Vis[pur])Continue; +c[++t]=pur; Avis[pur]=1; the             } +         } -vis[now]=0; $     } $     returndis[t]!=0x3f3f3f3f; - } - voidUpdata () { the     intmn=0x7fffffff; -      for(intI=t;i!=s;i= from[i]) {Wuyimn=std::min (Mn,flow[edge[i]); the     } -      for(intI=t;i!=s;i= from[i]) { Wuflow[edge[i]]-=mn; -flow[op[edge[i]]]+=mn; Aboutans+=mn*Cost[edge[i]]; $     } - } - voidMncostflow () { -ans=0; A     while(SPFA ()) Updata (); +printf"%d\n",-ans); the } - intMain () { $N=read (); K=read (); s=0; t=2*n+3; the      for(intI=1; i<=3*n;i++) thea[i]=read (); the      for(intI=1; i<=2*n+1; i++) theAdd (i+1, I,inf,0); -Add1, T,k,0); inAdd (S,2*n+2K0); the      for(intI=1; i<=n;i++) theAdd (i+1,1,1,-a[i]); About      for(inti=n+1; i<=n+n;i++) theAdd (i+1, i+1-N,1,-a[i]); the      for(inti=n+n+1; i<=n*3; i++) theAdd2*n+2, i-n+1,1,-a[i]); + Mncostflow (); -}

Bzoj 3550 Vacation