POJ3184 Ikki ' s Story i-road reconstruction (Max Stream)

Once the maximum flow is calculated, the capacity of all the edges of the full stream is +1, and then the augmented path is found.

1#include <cstdio>2#include <cstring>3#include <queue>4#include <algorithm>5 using namespacestd;6 #defineINF (1&LT;&LT;30)7 #defineMAXN 5558 #defineMAXM 111119 Ten structedge{ One     intV,cap,flow,next; A }EDGE[MAXM]; - intVs,vt,ne,nv; - intHEAD[MAXN]; the  - voidAddedge (intUintVintcap) { -Edge[ne].v=v; Edge[ne].cap=cap; edge[ne].flow=0; -Edge[ne].next=head[u]; head[u]=ne++; +Edge[ne].v=u; edge[ne].cap=0; edge[ne].flow=0; -EDGE[NE].NEXT=HEAD[V]; head[v]=ne++; + } A  at intLEVEL[MAXN]; - intGAP[MAXN]; - voidBFs () { -memset (level,-1,sizeof(level)); -Memset (Gap,0,sizeof(GAP)); -level[vt]=0; ingap[level[vt]]++; -queue<int>que; to Que.push (VT); +      while(!Que.empty ()) { -         intu=Que.front (); Que.pop (); the          for(intI=head[u]; i!=-1; I=Edge[i].next) { *             intv=edge[i].v; $             if(level[v]!=-1)Continue;Panax Notoginsenglevel[v]=level[u]+1; -gap[level[v]]++; the Que.push (v); +         } A     } the } +  - intPRE[MAXN]; $ intCUR[MAXN]; $ intISAP (BOOLstatue) { - BFS (); -memset (pre,-1,sizeof(pre)); thememcpy (Cur,head,sizeof(head)); -     intu=pre[vs]=vs,flow=0, aug=INF;Wuyigap[0]=NV; the      while(level[vs]<NV) { -         BOOLflag=false; Wu          for(int&i=cur[u]; i!=-1; I=Edge[i].next) { -             intv=edge[i].v; About             if(Edge[i].cap!=edge[i].flow && level[u]==level[v]+1){ $flag=true; -pre[v]=u; -u=v; -                 //aug= (Aug==-1?edge[i].cap:min (Aug,edge[i].cap)); AAug=min (aug,edge[i].cap-edge[i].flow); +                 if(v==VT) { the                     if(Statue&&aug)return 1; -flow+=; $                      for(u=pre[v]; V!=vs; v=u,u=Pre[u]) { theedge[cur[u]].flow+=; theedge[cur[u]^1].flow-=; the                     } the                     //Aug=-1; -aug=INF; in                 } the                  Break; the             } About         } the         if(flag)Continue; the         intMinlevel=NV; the          for(intI=head[u]; i!=-1; I=Edge[i].next) { +             intv=edge[i].v; -             if(Edge[i].cap!=edge[i].flow && level[v]<minlevel) { theMinlevel=Level[v];Bayicur[u]=i; the             } the         } -         if(--gap[level[u]]==0) Break; -level[u]=minlevel+1; thegap[level[u]]++; theu=Pre[u]; the     } the     returnflow; - } the intMain () { the     intn,m,a,b,c; thescanf"%d%d",&n,&m);94Xss0; vt=n-1; Nv=n; Ne=0; thememset (head,-1,sizeof(head)); the      while(m--){ thescanf"%d%d%d",&a,&b,&c);98 Addedge (a,b,c); About     } -ISAP (0);101     intCnt=0;102      for(intI=0; i<ne; i+=2){103         if(EDGE[I].FLOW!=EDGE[I].CAP)Continue;104++Edge[i].cap; the         if(ISAP (1)) ++CNT;106--Edge[i].cap;107     }108printf"%d", CNT);109     return 0; the}

POJ3184 Ikki ' s Story i-road reconstruction (Max Stream)