BZOJ1011: [HNOI2008]遥远的行星

 1 const maxn=100000+1000;
 2 var g:array[0..maxn] of int64;
 3     f,m:array[0..maxn] of extended;
 4     i,n:longint;
 5     y:extended;
 6 procedure init;
 7  begin
 8    readln(n,y);
 9    for i:=1 to n do readln(m[i]);
10    for i:=1 to n do g[i]:=trunc(i*y);
11  end;
12 procedure work1(x:longint);
13  var  i:longint;
14    begin
15      for i:=1 to g[x] do f[x]:=f[x]+m[x]*m[i]/(x-i);
16    end;
17 procedure work2(x:longint);
18  var i:longint;
19    begin
20      f[x]:=(f[x-100]/m[x-100])*((x-100-g[x-100]/2)/(x-g[x-100]/2));
21      for i:=g[x-100]+1 to g[x] do
22        f[x]:=f[x]+m[i]/(x-i);
23      f[x]:=f[x]*m[x];
24    end;
25 
26 procedure main;
27  begin
28    for i:=1 to n do f[i]:=0.0;
29    for i:=2 to n do
30     if i<=500 then work1(i) else work2(i);
31    for i:=1 to n do writeln(f[i]:0:6);
32  end;
33 begin
34   assign(input,‘input.txt‘);assign(output,‘output.txt‘);
35   reset(input);rewrite(output);
36   init;
37   main;
38   close(input);close(output);
39 end.