poj1703 Find them, Catch them

and check the set.

This problem has been wrong many times before.

See Code for analysis.

http://poj.org/problem?id=1703

1#include <cstdio>2#include <cstring>3#include <algorithm>4 using namespacestd;5 Const intMAXN = 1e5 +Ten;6 Const CharStr1[] ="Not sure yet.";7 Const CharStr2[] ="In different gangs.";8 Const CharStr3[] ="In the same gang.";9 intFA[MAXN], BELONG[MAXN], NEX[MAXN];Ten intN, M, U, V, K; One Charop; A  - intFatherintu) { -     //What would cause an INFINITE LOOP the     if(Fa[u] = =-1)returnu; -     intTEM =father (Fa[u]); -Belong[u] =Belong[tem]; -Fa[u] =tem; +     returntem; - } +  A voidsolve () { at     if(OP = ='D'){ -         if(Belong[u] = =-1&& Belong[v] = =-1){ -             //The simplest case -Belong[u] = k++; -BELONG[V] = k++; -Nex[u] =v; inNEX[V] =u; -             return; to         } +         if(Belong[u]! =-1&& Belong[v] = =-1){ -             //Notice that's never mentioned, but u are already processed the             //since is U-vistied, u got its partner *             intFu = Father (u), FU1 =father (Nex[u]); $             //draw a line from V to U1Panax NotoginsengFA[V] =FU1; -NEX[V] =Fu; theBELONG[V] =BELONG[FU1]; +             return; A             //match a virtue partner for node U the         } +         if(Belong[u] = =-1&& Belong[v]! =-1){ -             intFV = Father (v), Fv1 =father (Nex[v]); $Fa[u] =Fv1; $Nex[u] =FV; -Belong[u] =BELONG[FV1]; -             return; the         } -         if(Belong[u]! =-1&& Belong[v]! =-1){Wuyi             //notice that both U and V are already visited the             intFu = Father (u), FU1 =father (Nex[u]); -             intFV = Father (v), Fv1 =father (Nex[v]); Wu             intBU = Belong[fu] >>1; -             intBV = BELONG[FV] >>1; About             if(Bu >BV) { $                 //V is relatively primitive -FA[FU] =Fv1; -FA[FU1] =FV; -                 return; A             } +             if(Bu <BV) { theFA[FV] =FU1; -FA[FV1] =Fu; $                 return; the             } the         } the     } the     if(OP = ='A'){ -         intFu =father (U); in         intFV =father (v); the         if(Belong[fu] = =-1|| BELONG[FV] = =-1) puts (str1); the         Else if(Belong[fu] = =BELONG[FV]) puts (STR3); About         Else if(Belong[fu] = = (1^BELONG[FV])) Puts (STR2); the         Elseputs (str1); the     } the } +  - intMain () { theFreopen ("In.txt","R", stdin);Bayi     intT; thescanf"%d", &T); the      while(t--){ -scanf"%d%d", &n, &m); -Memset (Belong,-1,sizeofbelong); thememset (FA,-1,sizeofFA); theK =0; the          for(inti =0; I < m; i++){ thescanf"%c%d%d", &op, &u, &v); - solve (); the         } the     } the}

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poj1703 Find them, Catch them