Bzoj 4116 Wf2015 Tours Tarjan

The topic is: given a piece n A point m The side of the graph, you need to select a number of color categories k , and then use this k Color to each edge, requiring that for any simple ring in the graph, the number of edges of each color is the same, all feasible k

Consider the edge set E Split into subsets { E 1 , E 2 , E 3 ,..} That satisfies any simple ring that can be split into subsets and that does not exist after the two subset is merged, then the answer is GCD{| E 1 |,| E 2 |,| E 3 |,..} All the approximate

So how do you determine these subsets?

"Try to delete each non-bridged edge and count how many sides have become new bridges. Get the number of the +1 gcd. "--petr
Tourist brush down the Twitter, the mouth with a touch of mystery, with the Battle of the national atmosphere of the smile. (Giant fog

We try to delete each non-bridge side, then the new side of the bridge must be the same set as the non-bridge, but I will not prove it.

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#define M 2020using namespace STD;structedge{intx, y;} EDGES[M];structabcd{intTo,num,next;} table[m<<1];inthead[m],tot=1;intN,m,ans;intDpt[m],low[m],t;BOOLIS_BRIDGE[M],TO_BE_BRIDGE[M],V[M];voidInitialize () {memset(Head,0,sizeofHead); tot=1;memset(DPT,0,sizeofDPT);memset(Low,0,sizeofLow);memset(To_be_bridge,0,sizeofTo_be_bridge);}voidADD (intXintYintz) {table[++tot].to=y;    Table[tot].num=z;    TABLE[TOT].NEXT=HEAD[X]; Head[x]=tot;}voidTarjan (intXintFrom) {intI Dpt[x]=low[x]=++t; for(I=head[x];i;i=table[i].next)if(i^from^1)        {if(Dpt[table[i].to]) low[x]=min (low[x],dpt[table[i].to]);Else{Tarjan (table[i].to,i); Low[x]=min (low[x],low[table[i].to]);if(Low[table[i].to]>dpt[x]) to_be_bridge[table[i].num]=true; }        }}intMain () {intI,j;Cin>>n>>m; for(i=1; i<=m;i++) {scanf("%d%d", &AMP;EDGES[I].X,&AMP;EDGES[I].Y);        ADD (Edges[i].x,edges[i].y,i);    ADD (Edges[i].y,edges[i].x,i); } for(i=1; i<=n;i++)if(!dpt[i]) Tarjan (I,0);memcpy(Is_bridge,to_be_bridge,sizeofIs_bridge); for(i=1; i<=m;i++)if(!v[i]&&!is_bridge[i]) {intCnt=1; v[i]=true; Initialize (); for(j=1; j<=m;j++)if(j!=i)                    {ADD (EDGES[J].X,EDGES[J].Y,J);                ADD (EDGES[J].Y,EDGES[J].X,J); } for(j=1; j<=n;j++)if(!dpt[j]) Tarjan (J,0); for(j=1; j<=m;j++)if(!is_bridge[j]&&to_be_bridge[j]) v[j]=true, ++cnt;        ANS=__GCD (ANS,CNT); } for(i=1; i<=ans;i++)if(ans%i==0)printf("%d%c", I,i==ans?' \ n ':"');return 0;}

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Bzoj 4116 Wf2015 Tours Tarjan