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.
