P1697: [Usaco2007 Feb]Cow Sorting牛排序

这是一道置换群的裸题=-=，先拿来试试手对着打，以后应该会更加熟练吧！

 const maxn=;
 var n,i,j,maxx,minx,now,len,cursum,tmin,sum:longint;
 p:array[..maxn] of boolean;
 agr,pos:array[..maxn] of longint;
 function min(a,b:longint):longint;
 begin
   if a>b then exit(b)
     else exit(a);
 end;
 begin
   readln(n);
   minx:=maxn;
   for i:= to n do
     begin
       readln(agr[i]);
       inc(pos[agr[i]]);
       minx:=min(minx,agr[i]);
       maxx:=maxx+agr[i]-min(maxx,agr[i]);
     end;
   //writeln(minx,' ',maxx);
   for i:= to maxx do
     inc(pos[i],pos[i-]);
   fillchar(p,sizeof(p),true);
   for i:= to n do
     if p[i] then
       begin
         now:=i;
         tmin:=agr[i];
         len:=;
         cursum:=;
         while p[now] do
           begin
             inc(len);
             tmin:=min(tmin,agr[now]);
             inc(cursum,agr[now]);
             p[now]:=false;
             now:=pos[agr[now]];
           end;
         if len> then inc(sum,cursum);
         if len> then inc(sum,min((len-)*tmin,minx*(len+)+tmin));
      end;
   writeln(sum);
 end.

(转载请注明出处：http://www.cnblogs.com/Kalenda/)