You must use 'Longint' type in the sequence,
But 'Extended' in the coefficient!

Hope this will be helpful.
Good luck.

program t1133;
var a1,a2,i1,j1,n,j,i,t1:longint;
    b,x1,y1,t:extended;
    f:array[0..2000]of extended;
    a:array[-2000..2000]of extended;
begin
     readln(i1,x1,j1,y1,n);
     if i1>j1 then begin t1:=i1; i1:=j1; j1:=t1; t:=x1; x1:=y1;
y1:=t; end;
     f[1]:=1; f[2]:=1;
     for i:=3 to j1-i1 do f[i]:=f[i-1]+f[i-2];
     b:=trunc((y1-x1*f[j1-i1-1])/(f[j1-i1]));
     a[i1]:=x1; a[i1+1]:=b;
     if n>i1 then
        for i:=i1+2 to n do
            a[i]:=a[i-1]+a[i-2];
     if n<i1 then
        for i:=i1-1 downto n do
            a[i]:=a[i+2]-a[i+1];
     writeln(a[n]:0:0);
end.

> program t1133;
> var a1,a2,i1,j1,n,j,i,t1:longint;
>     b,x1,y1,t:extended;
>     f:array[0..2000]of extended;
>     a:array[-2000..2000]of extended;
> begin
>      readln(i1,x1,j1,y1,n);
>      if i1>j1 then begin t1:=i1; i1:=j1; j1:=t1; t:=x1; x1:=y1;
> y1:=t; end;
>      f[1]:=1; f[2]:=1;
>      for i:=3 to j1-i1 do f[i]:=f[i-1]+f[i-2];
>      b:=trunc((y1-x1*f[j1-i1-1])/(f[j1-i1])); (*)
>      a[i1]:=x1; a[i1+1]:=b;
>      if n>i1 then
>         for i:=i1+2 to n do
>             a[i]:=a[i-1]+a[i-2];
>      if n<i1 then
>         for i:=i1-1 downto n do
>             a[i]:=a[i+2]-a[i+1];
>      writeln(a[n]:0:0);
> end.
>
Pay attention that you use 'trunc' in your program (the line
with '*').It is the same as use 'Longint'.

f:array[0..2000]of extended;
Pay attention that this must use 'extended';
Do you understand??

No, it doesn't need to be. Just use Longint, that's OK!

In array F, you must use 'Extended', but in array A, you MUST
use 'Longint'. In my first saying I meant this!

Oh!
No wonder I always got wrong answer!

Try to use trunc (((y1-x1*f[j1-i1-1])/(f[j1-i1]))+1e-6).

#include <iostream.h>
#include <iostream>
long p(long q)
{return (q+1000);}
int main()
{
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "rt", stdin);
    freopen("output.txt", "wt", stdout);
    #endif
    long double  a[2002];
    long double  c[2002];
    long double  x[2002];
    long i,j,n,t;
    for (t=0;t<2002;t++){a[t]=c[t]=x[t]=0;}
    cin>>i;
    cin>>a[p(i)];
    cin>>j;
    cin>>a[p(j)]>>n;
    if (i>j)
    {
    t=i;
    i=j;
    j=t;
    }//i<j
    c[p(i)]=1;x[p(i)]=0;
    c[p(i+1)]=0;x[p(i+1)]=1;
    for (t=i+2;t<j+1;t++){c[p(t)]=c[p(t-1)]+c[p(t-2)];x[p(t)]=x[p(t-1)]+x[p(t-2)];}
    a[p(i+1)]=a[p(j)]/x[p(j)]-c[p(j)]/x[p(j)]*a[p(i)];
    if (i<=n)
    {
        for (t=i+2;t<n+1;t++)
        {a[p(t)]=a[p(t-1)]+a[p(t-2)];}
    }
    if (i>n)
    {
        for (t=i-1;t>n-1;t--){a[p(t)]=a[p(t+2)]-a[p(t+1)];}
    }
    cout<<(long)a[p(n)];
    return 0;
}

Use round! When integers will be <0, trunc(-1+1e-6) will be equals to 0!

Edited by author 10.11.2007 16:44

Edited by author 10.11.2007 16:47