UVA 11374 Airport Express (single source shortest, Dijkstra, deformed)

Test instructions: To a picture, from the s point to the e point, the figure has two non-edge in two sets, the first set can be used indefinitely, the second set of edges can only pick 1. Q How to make the shortest distance? The output path, whichever edge in the second set is used, the shortest distance.

Ideas:

(1) Simple and easy to operate method: Since the second set of the side can only have 1, on the poor lift these edges, the possible edge set to find the shortest path, while recording 3 answers. The complexity is O (m*k).

(2) The time complexity is low: may wish to ask from S to each other point distance d1[i], then the distance from E to each other point d2[i], next to the second set of each edge u-v, the shortest distance is d1[u]+dis[u][v]+d2[v], notice the edge is non-direction. Trouble in the record path, or very easy to operate. The complexity is O (2m+k).

Here's the code for the first method:

1#include <bits/stdc++.h>2 #defineLL Long Long3 #definePII pair<int,int>4 #defineINF 0x7f7f7f7f5 using namespacestd;6 Const intn=1010;7 intN, M, K;8vector<int>Vect[n];9 intedge_cnt;Ten structnode One { A     int  from, to, dis, tag; - node () {}; -Nodeint  from,intTo,intDisintTAG): from( from), to, dis (dis), tag (tag) {}; the}edge[n*5]; -  -  -  + voidAdd_node (int  from,intTo,intDisinttag) - { +Edge[edge_cnt]=node ( from, To,dis,tag); Avect[ from].push_back (edge_cnt++); at } -  -  - intTag[n], dist[n], vis[n], path[n]; - intDijkstraintSinte) - { inmemset (Dist,0x7f,sizeof(Dist)); -memset (Tag,0,sizeof(tag)); tomemset (Vis,0,sizeof(Vis)); +memset (Path,0,sizeof(path)); -  thepriority_queue<pii,vector<pii>,greater<pii> >que; *Que.push (Make_pair (0, s)); $dist[s]=0;Panax Notoginseng  -      while(!que.empty ()) the     { +         intx=Que.top (). Second; A Que.pop (); the         if(Vis[x])Continue; +vis[x]=1; -          for(intI=0; I<vect[x].size (); i++) $         { $Node e=Edge[vect[x][i]]; -             if(e.tag>0&& dist[e.to]>dist[x]+E.dis) -             { thedist[e.to]=dist[x]+E.dis; -path[e.to]=x;Wuyi                 if(e.tag==2) the                 { -tag[e.to]=true;//We have a quick line at this point. Wu                 } - Que.push (Make_pair (dist[e.to],e.to)); About             } $         } -     } -     returnDist[e]; - } A  + voidCalintS,inte) the { -vector<int>ans; $     intquick=0, Big=dijkstra (s,e), d=e;//run first, no quick lines. the  the      while(d) the     { the Ans.push_back (d); -D=Path[d]; in     } the  the      for(inti=m*2; i< (m+k) *2; i+=2)//Every single quick line you can use. About     { theedge[i].tag=2; theedge[i+1].tag=2; the  +         intdis=Dijkstra (s,e); -         if(dis<big) the         {Bayibig=dis; the ans.clear (); the             intEd=e, tmp=0; -              while(ed) -             { the                 if(Tag[ed]) tmp=path[ed];//It might not have been used . the Ans.push_back (ed); theEd=path[ed]; the             } -quick=tmp;//if not, it will be updated to 0 in time. the         } theedge[i].tag=0; theedge[i+1].tag=0;94     } the  the Reverse (Ans.begin (), Ans.end ()); theprintf"%d", ans[0]);//Be careful with the output format98      for(intI=1; I<ans.size (); i++) printf ("%d", Ans[i]); Aboutprintf"\ n"); - 101     if(quick) printf ("%d\n", quick);102     ElsePuts"Ticket not used");//don't forget.103 104printf"%d\n", big); the }106 107 intMain ()108 {109Freopen ("Input.txt","R", stdin); the     ints=0, E, A, B, C, ttt=0;111      while(~SCANF ("%d%d%d", &n, &s, &e)) the     {113         if(TTT) printf ("\ n"); ttt++;//format Ah!  theEdge_cnt=0; theMemset (Edge,0,sizeof(Edge)); the          for(intI=0; i<=n; i++) vect[i].clear ();117scanf"%d",&m);118          for(intI=0; i<m; i++)119         { -scanf"%d%d%d",&a,&b,&c);121Add_node (A,b,c,1);122Add_node (B,a,c,1);123         }124scanf"%d",&k); the          for(intI=0; i<k; i++)126         {127scanf"%d%d%d",&a,&b,&c); -Add_node (A,b,c,0);129Add_node (B,a,c,0); the         }131 cal (s,e); the     }133     return 0;134}

AC Code

UVA 11374 Airport Express (single source shortest, Dijkstra, deformed)