BZOJ4010 [HNOI2015] dish making

The first is the greedy thought ... We grew up to the top of each place.

Build the inverse diagram, and then sort the topology, each time to find the $deg=0$ point of the largest, so you can ensure that the number of small as far as possible in the back

Finally the order upside down the output is good ...

1 /**************************************************************2 problem:40103 User:rausen4 language:c++5 result:accepted6 time:900 Ms7 memory:3936 KB8 ****************************************************************/9  Ten#include <cstdio> One#include <cstring> A#include <queue> -   - using namespacestd; the Const intN = 1e5 +5; -   - structEdge { -     intnext, to; +Edgeint_n =0,int_t =0): Next (_n), to (_t) {} - } E[n]; +   A intN, M; at intfirst[n], tot; - intDeg[n], q[n]; - intT[n], now, v[n]; - intAns[n]; -Priority_queue <int>h; -   inInlineintread (); -   toInlinevoidAdd_edge (intXinty) { +E[++tot] = Edge (first[x], y), first[x] =tot; -++Deg[y]; the } *   $ #defineP Q[l]Panax Notoginseng #defineY e[x].to - BOOLcheck_circle () { the     Static intI, L, R, X; +      for(R =0, i =1; I <= N; ++i)if(Deg[i] = =0) Q[++r] =i; A      for(L =1; L <= R; ++l) the          for(x = first[p]; x; x =e[x].next) +             if(--deg[y] = =0) Q[++r] =y; -     returnr! =N; $ } $   -InlineintBFsints) { -     Static intL, R, X; the++Now ; -Q[l = r =1] =s;Wuyi      for(; l <= R; + +)l) the          for(x = first[p]; x; x = e[x].next)if(!V[y]) { -++Deg[y]; Wu             if(T[y]! =Now ) -Q[++r] = y, t[y] =Now ; About         } $ } - #undefP -   -Inlinevoid Get(ints) { A     Static intp, x; +      while(!h.empty ()) H.pop (); theH.push (s), v[s] =1; -      while(!H.empty ()) { $p =h.top (), H.pop (); theans[++ans[0]] =p; the          for(x = first[p]; x; x = e[x].next)if(!V[y]) the             if(--deg[y] = =0) H.push (y), v[y] =1; the     } - } in #undefY the   the intMain () { About     intT, I, X, y; theT =read (); the      while(t--) { then = Read (), M = Read (), tot = now =0; +memset (First,0,sizeof(first)); -memset (V,0,sizeof(v)); thememset (deg,0,sizeof(deg));Bayimemset (T,0,sizeof(t)); the          for(i =1; I <= m; ++i) { thex = Read (), y =read (); - Add_edge (y, x); -         } the         if(Check_circle ()) { thePuts"impossible!"); the             Continue; the         } -          for(i =1; I <= N; ++i)if(!V[i]) { the BFS (i); the             Get(i); the              for(; ans[0]; --ans[0]) printf ("%d", ans[ans[0]]);94         } thePuts""); the     } the     return 0;98 } About   -InlineintRead () {101     Static intx;102     Static Charch;103x =0, ch =GetChar ();104      while(Ch <'0'||'9'<ch) theCH =GetChar ();106      while('0'<= CH && Ch <='9') {107x = x *Ten+ CH-'0';108CH =GetChar ();109     } the     returnx;111}

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BZOJ4010 [HNOI2015] dish making