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.