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  1. const maxn=70000;
  2. type mang=array[0..maxn+2] of longint;
  3. var a:mang; n,i:longint;      res:int64;
  4. function cinv(len:longint;var a:mang):int64;
  5. var i,j,k,nl,nr:longint;
  6.     x,y,z:int64;
  7.     l,r:mang;
  8. begin
  9.     if (len<=1) then begin cinv:=0;          exit; end;
  10.     nl:=len div 2;        nr:=len-nl;
  11.     for i:=0 to nl-1 do l[i]:=a[i];
  12.     for i:=nl to len-1 do r[i-nl]:=a[i];
  13.     x:=cinv(nl,l);             y:=cinv(nr,r);
  14.     j:=0;                   r[nr]:=maxlongint;        l[nl]:=maxlongint;
  15.     z:=0;
  16.     for i:=0 to nl-1 do begin
  17.           while l[i]>r[j] do inc(j);
  18.           z:=z+j;
  19.     end;
  20.      i:=0;j:=0;
  21.     for k:=0 to len-1 do begin
  22.           if (l[i]<=r[j]) then begin
  23.                a[k]:=l[i];     inc(i);
  24.           end else begin
  25.                a[k]:=r[j];     inc(j);
  26.           end;
  27.     end;
  28.     cinv:=x+y+z;
  29. end;
  30. begin
  31.     assign(input,'');          reset(input);
  32.     assign(output,'');        rewrite(output);
  33.     //readln(n);      for i:=0 to n-1 do   read(a[i]);
  34.     n:=maxn;          for i:=0 to n-1 do   a[i]:=n-i;
  35.     res:=cinv(n,a);
  36.     write(res);
  37.     close(input);                  close(output);
  38. end.
Runtime error #stdin #stdout 0.01s 8064KB
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stdin
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Standard input is empty
stdout
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Standard output is empty
https://ideone.com/9LjISb
language:
Pascal (fpc 3.0.4)
created:
11 years ago
visibility:
public

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