(connected + violent) UVA-208 Firetruck

Original title Link:

More trouble, do not hang, you can on the UVA live find, you can also use virtual judge hanging problems.

Test instructions

Outputs all paths from 1 to K and cannot be repeated

Analysis:

The problem is simple deep search backtracking, using an array to record the path, the output when the condition is satisfied. Purple Book said need to first determine whether 1 to K is connected, otherwise it will time out. Made a direct deep search, sure enough tle. So we need to get connected first.

The method of connecting is (can be thought of):

1, DFS and BFS, both feel the same, but I choose the BFS

2, floyd,n^3 complexity, but more rude direct, also better write

3. To be added

Sentiment:

No pre-judgment connected 3000ms timeout, sentenced to connect on 0ms seconds ac, feeling ah.

Code:

1#include <iostream>2#include <cstdio>3#include <cstring>4#include <vector>5#include <Set>6#include <map>7#include <algorithm>8#include <string>9#include <queue>Ten#include <cmath> One#include <stack> A#include <cctype> -#include <list> -  the #definell Long Long - #defineull unsigned long Long - #defineVName (name) (#name) - #defineDebug (a) Cout<<vname (a) << "=" << (a) <<endl; +  - using namespacestd; +  A Const intMAXN =100010; at Const intINF =1<< -; - intK; -vector<int> edge[ A]; -queue<int>Q; - BOOLvis[ A]; - introad[ A]; in intsum; -  to voidinit () { +memset (Vis,0,sizeof(Vis)); -      for(intI=0; i< A; i++) { the edge[i].clear (); *     } $sum=0;Panax Notoginseng } -  the //a very standard wide-search + BOOLBFsintv) { A     BOOLmark[ A]= {0}; the      while(!q.empty ()) Q.pop (); + Q.push (v); -mark[v]=1; $      while(!Q.empty ()) { $         ints=Q.front (); - Q.pop (); -         if(s==k)return true;//find the K point and return the          for(intI=0; I<edge[s].size (); i++) { -             if(!Mark[edge[s][i]]) {Wuyi Q.push (Edge[s][i]); themark[edge[s][i]]=1; -             } Wu         } -     } About     return false; $ } -  -  - voidDfsintVintCNT) { ARoad[cnt]=v;//Record Path +     if(v==k) { the          for(intI=0; i<cnt; i++) { -printf"%d", Road[i]); $         } theprintf"%d\n", road[cnt]); thesum++;//number of record paths the         return ; the     } -      for(intu=0; U<edge[v].size (); u++) { in         if(!Vis[edge[v][u]]) { thevis[v]=1;//Mark Origin theDFS (edge[v][u],cnt+1); Aboutvis[v]=0;//Backtracking the         } the     } the } +  - intMain () { the     //Iostream::sync_with_stdio (false);Bayi  the #ifndef Online_judge theFreopen ("In.txt","R", stdin); -     //freopen ("OUT.txt", "w", stdout); - #endif the  the     intKace=0; the      while(~SCANF ("%d",&k)) { theInit ();//preprocessing empty -         intV,u; the          while(SCANF ("%d%d",&v,&u)) { the             if(v==0&&u==0) Break; the edge[v].push_back (u);94Edge[u].push_back (v);//Non-directional graph bidirectional connecting edge the         } the          for(intI=0; i< A; i++) { theSort (Edge[i].begin (), Edge[i].end ());//sorting, it is convenient to let Dfs out of the path by dictionary order98         } Aboutprintf"Case %d:\n",++kace); -         if(BFS (1)) DFS (1,0);//if connected, start deep search101printf"there is%d routes from the firestation to Streetcorner%d.\n", sum,k);102     }103     return 0;104}

(connected + violent) UVA-208 Firetruck