CF 217A （森林数）

求森林数，裸的并查集

Program c;var   n,i,j,ans:longint;   map:array[1..100,1..2] of longint;   f:array[1..100] of longint;function getfather(a:longint):longint;begin   if f[a]=a then exit(a);   f[a]:=getfather(f[a]);   exit(f[a]);end;procedure union(a,b:longint);begin   f[getfather(a)]:=f[getfather(b)];end;begin   read(n);   for i:=1 to n do   begin      f[i]:=i;      read(map[i,1],map[i,2]);      for j:=1 to i-1 do         if (map[i,1]=map[j,1]) or (map[i,2]=map[j,2]) then            union(i,j);   end;   ans:=0;   for i:=2 to n do      if getfather(i)<>getfather(i-1) then      begin         inc(ans);         union(i,i-1);      end;   writeln(ans);end.