HDU 5154 Harry and magical computer to the graph ring

Topic Links:

http://acm.hdu.edu.cn/showproblem.php?pid=5154

Exercises

There is a circular to the graph.

1, with DFS, the node being accessed is labeled-1, the node that has been visited is marked as 1, the node that has not been visited is marked as 0, and if access to-1 node description is said to have a ring.

1#include <iostream>2#include <cstdio>3#include <cstring>4#include <cmath>5 using namespacestd;6typedefLong LongLL;7 8 intn,m;9 Ten Const intmaxm=10000+Ten; One Const intmaxn=111; A  - structedge{ -     intV,ne; theEdge (intVintne): V (v), NE (NE) {} - Edge () {} - }EGS[MAXM]; -  + intHead[maxn],tot; - intVIS[MAXN]; +  A voidAddedge (intUintv) { ategs[tot]=Edge (V,head[u]); -head[u]=tot++;  - } -  - BOOLDfsintcur) { -vis[cur]=-1; in     intp=Head[cur]; -      while(p!=-1){ toEdge &e=Egs[p]; +         if(vis[e.v]==0){ -             if(Dfs (E.V))return true; the         } *         Else if(vis[e.v]==-1){ $             return true;Panax Notoginseng         }  -p=e.ne; the     } +vis[cur]=1; A     return false; the } +  - voidinit () { $memset (head,-1,sizeof(head)); $memset (Vis,0,sizeof(Vis)); -tot=0; - } the  - intMain () {Wuyi      while(SCANF ("%d%d", &n,&m) = =2&&N) { the init (); -          while(m--){ Wu             intu,v; -scanf"%d%d",&u,&v); About Addedge (u,v); $         }  -         intsu=1; -          for(intI=1; i<=n;i++){ -             if(vis[i]==0){ A                 if(Dfs (i)) { +su=0; Break; the                 } -             }  $         } the         if(SU) puts ("YES"); the         ElsePuts"NO");  the     } the     return 0; -}

2, topological sorting.

1#include <iostream>2#include <cstdio>3#include <cstring>4#include <cmath>5#include <queue>6 using namespacestd;7typedefLong LongLL;8 9 intN, M;Ten  One Const intMAXM =10000+Ten; A Const intMAXN =111; -  - structEdge { the     intV, NE; -Edge (intVintne): V (v), NE (NE) {} - Edge () {} - }EGS[MAXM]; +  - intHEAD[MAXN], tot; + intIND[MAXN]; A  at voidAddedge (intUintv) { -Egs[tot] =Edge (V, Head[u]); -Head[u] = tot++; - } -  - voidinit () { inMemset (Head,-1,sizeof(head)); -memset (Ind,0,sizeof(Ind)); totot =0; + } -  the intMain () { *      while(SCANF ("%d%d", &n, &m) = =2&&N) { $ init ();Panax Notoginseng          while(m--) { -             intu, v; thescanf"%d%d", &u, &v); + Addedge (U, v); Aind[v]++; the         } +queue<int>Q; -          for(inti =1; I <= N; i++) { $             if(Ind[i] = =0) Q.push (i); $         } -          while(!Q.empty ()) { -             intU =Q.front (); Q.pop (); the             //printf ("v:%d\n", v); -             intp =Head[u];Wuyi              while(P! =-1) { theedge& e =Egs[p]; -ind[e.v]--; Wu                 if(IND[E.V] = =0) Q.push (E.V); -p =e.ne; About             } $         } -         intSu =1; -          for(inti =1; I <= N; i++) { -             if(Ind[i]) {su =0; Break; } A         } +         if(SU) puts ("YES"); the         ElsePuts"NO"); -     } $     return 0; the}

HDU 5154 Harry and magical computer to the graph ring