pku1674 Sorting by Swapping

这道题需要涉及到置换群的知识，只需知道一个定理。

最小交换次数=元素个数-环的个数。

program pku1674(input,output);
var
    number :array[0..11000] of integer;
    v       :array[0..11000] of boolean;
    n,cases:longint;
    answer :longint;
procedure init;
var
    i:longint;
begin
    readln(n);
    for i:=1 to n do
        read(number[i]);
    fillchar(v,sizeof(v),false);
end;{ init }
procedure main;
var
    now,i:longint;
begin
    answer:=0;
    for i:=1 to n do
    if not v[i] then
    begin
        inc(answer);
        v[i]:=true;
        now:=number[i];
        while not v[now] do
        begin
            v[now]:=true;
            now:=number[now];
        end;
    end;
end;{ main }
procedure print;
begin
    writeln(n-answer);
end;{ print }
begin
    readln(cases);
    while cases>0 do
    begin
        dec(cases);
        init;
        main;
        print;
    end;
end.