POJ 3177(带重边的连通图的双连通分量）

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题目大意：求带重边的连通图至少加几条边变成双连通图

POJ 3352+重边

用邻接矩阵的表示无压力

Program P3177;const   maxn=1000;   maxm=1000;var   n,m,i,j,x,y:longint;   b:array[1..maxn,1..maxn] of boolean;   indegree,c,a,low:array[1..maxn] of longint;   time:longint;function min(a,b:longint):longint;begin   if a<b then exit(a) else exit(b);end;function max(a,b:longint):longint;begin   if a>b then exit(a) else exit(b);end;procedure tarjan(k,father:longint);var   i,j:longint;begin   inc(time);   a[k]:=time;   low[k]:=time;   c[k]:=1;   for i:=1 to n do   begin      if (b[i,k]) and (i<>father) and (a[i]<a[k]) then      begin         if c[i]=0 then         begin            tarjan(i,k);            low[k]:=min(low[k],low[i]);         end;         if (c[i]=1) and (i<>father) then         begin            low[k]:=min(low[k],a[i]);         end;      end;   end;   c[k]:=2;end;procedure main;var   i,j,tot:longint;begin   fillchar(a,sizeof(a),0);   fillchar(low,sizeof(low),0);   fillchar(c,sizeof(c),0);   fillchar(indegree,sizeof(indegree),0);   time:=0;   tarjan(1,0);   for i:=1 to n do      for j:=i+1 to n do         if (low[i]<>low[j]) and (b[i,j]) then         begin            inc(indegree[low[i]]);            inc(indegree[low[j]]);         end;   tot:=0;   for i:=1 to n do if indegree[i]=1 then inc(tot);   writeln((tot+1) div 2);end;begin   fillchar(b,sizeof(b),false);   read(n,m);   for i:=1 to m do   begin      read(x,y);      b[x,y]:=true;      b[y,x]:=true;   end;   main;end.