BZOJ1927[SDOI2010] Star Racing

BZOJ1927[SDOI2010] Star Racing

Test instructions

The race is made up of n planets and M two-way interstellar routes, each of which has a different gravitational value. The competition requires riders to visit each of the N planets at exactly once, starting from a celestial body that does not have any route between the N planets. Racing Super Electric Donkey in high-speed sailing mode, sailing along the interstellar route, but only from each planet to the gravity of the larger planet. In the ability to burst mode, the Super Electric Donkey after a period of positioning, can instantly move to any planet. The shortest time to complete the game. n≤800,m≤15000

Exercises

Cost flow. Each point is split into X, y two points, the source is connected to each Y-point, the flow is 1, and the cost is the positioning time for the planet, which means passing through the planet directly. The source is then connected to each x point flow 1, the cost 0, each y point to the connecting edge, traffic 1, the cost 0. X and Y are connected by "interplanetary Route", which means from X point to Y point. We don't care where we go from here to the planet, we only consider that each planet can only pass once. Reflection: The mentally retarded at the beginning to understand any of the questions, and later found that they are capable of explosive mode needs to be restricted by gravity, not examining retired Qaq

Code:

1#include <cstdio>2#include <cstring>3#include <algorithm>4#include <queue>5 #defineInc (I,J,K) for (int i=j;i<=k;i++)6 #defineMAXN 20007 #defineINF 0X3FFFFFFF8 using namespacestd;9 Ten structe{intF,t,c,w,n;}; E es[maxn* +];intESS,G[MAXN]; OneInlinevoidPeintFintTintCintW) { AEs[++ess]= (e) {f,t,c,w,g[f]}; g[f]=ess; Es[++ess]= (e) {t,f,0,-w,g[t]}; g[t]=ess; - } - voidInit () {ess=-1; memset (g,-1,sizeof(g));} the intD[MAXN],FR[MAXN];BOOLINQ[MAXN]; Queue <int>Q; - BOOLSPFA (intSintt) { -      while(!q.empty ()) Q.pop (); memset (INQ,0,sizeof(INQ)); memset (d,-1,sizeof(d)); -inq[s]=1; d[s]=0; Q.push (s); fr[s]=-1; +      while(!Q.empty ()) { -         intX=q.front (); Q.pop (); inq[x]=0; +          for(inti=g[x];i!=-1; i=es[i].n)if(es[i].c&& (d[es[i].t]==-1|| d[es[i].t]>d[x]+ES[I].W)) { AD[ES[I].T]=D[X]+ES[I].W; Fr[es[i].t]=i;if(!inq[es[i].t]) inq[es[i].t]=1, Q.push (es[i].t); at         } -     } -     returnd[t]!=-1; - } - intAdvancedintSintt) { -     intA=inf,c=0; in      for(inti=fr[t];i!=-1; I=FR[ES[I].F]) a=min (a,es[i].c); -      for(inti=fr[t];i!=-1; I=FR[ES[I].F]) es[i].c-=a,es[i^1].c+=a,c+= (A *ES[I].W); to     returnC; + } - intMaxflowmincost (intSintt) { the     intC=0; while(SPFA (s,t)) c+=advanced (s,t);returnC; * } $ intn,m,s,t;Panax Notoginseng intMain () { -scanf"%d%d", &n,&m); s=0; t=2*n+1; init (); theInc (I,1, N) {intA scanf"%d", &a); PE (S,I+N,1, a);} +Inc (I,1, m) {intA,b,c; scanf"%d%d%d", &a,&b,&c); PE (min (A, b), Max (A, b) +n,1, c);} AInc (I,1, n) PE (s,i,1,0), PE (I+N,T,1,0); theprintf"%d", Maxflowmincost (s,t));return 0; +}

20160527

BZOJ1927[SDOI2010] Star Racing