kolokrek

MODULE kolok;
FROM InOut IMPORT WriteString,WriteLn,ReadInt,WriteInt;
CONST maxn=30;
      maxr=20;
      sk={0,1,4,9};
TYPE niz= ARRAY [0..maxr] OF INTEGER;
(*A*)
PROCEDURE grec(n,r:INTEGER):INTEGER; FORWARD;
PROCEDURE frec(n,r:INTEGER):INTEGER;
BEGIN
  IF n<r THEN
    RETURN n
  ELSE
    IF n MOD 10 IN sk THEN
      RETURN frec(n-r,r)-frec(n-r+1,r)+grec(n-r+2,r)-grec(n-r+1,r)
    ELSE
      RETURN -frec(n-1,r)+grec(n-r,r)-frec(n-r+2,r)-grec(n-1,r)
    END;
  END;
END frec;
PROCEDURE grec(n,r:INTEGER):INTEGER;
BEGIN
  IF n<r THEN
    RETURN -n
  ELSE
    IF n DIV 2 = 0 THEN
      RETURN 3*frec(n-2,r)+2*(grec(n-r+2,r)-frec(n-r+3,r))-grec(n-r,r);
    ELSE
      RETURN -grec(n-r+1,r)-frec(n-2,r)
    END;
  END;
END grec;
(*B*)
PROCEDURE frec2(n,r:INTEGER):INTEGER;
  PROCEDURE FG(f,g:niz; i:INTEGER):INTEGER;
  VAR j:INTEGER;
  BEGIN
    IF i>n THEN
      RETURN f[r]
    ELSE
      IF i MOD 10 IN sk THEN
        f[r]:=f[0]-f[1]+g[2]-g[1];
      ELSE
        f[r]:=-f[r-1]+g[0]-f[2]-g[r-1];
      END;
      IF i DIV 2 = 0 THEN
        g[r]:=3*f[r-2]+2*(g[2]-f[3])-g[0];
      ELSE
        g[r]:=-g[1]-f[r-2];
      END;
      FOR j:=0 TO r-1 DO
        f[j]:=f[j+1];
    g[j]:=g[j+1];
      END;
      RETURN FG(f,g,i+1);
    END;
  END FG;
VAR f,g:niz;
    j:INTEGER;
BEGIN
  IF n<r THEN
    RETURN n
  ELSE
    FOR j:=0 TO r-1 DO
      f[j]:=j;
      g[j]:=-j;
    END;
    RETURN FG(f,g,r);
  END;
END frec2;
(*C*)
PROCEDURE fiter(n,r:INTEGER):INTEGER;
VAR f,g:niz;
    i,j:INTEGER;
BEGIN
  FOR i:=0 TO r-1 DO
    f[i]:=i;
    g[i]:=-i;
  END;
  IF n<r THEN
    RETURN f[n]
  ELSE
    FOR i:=r TO n DO
      IF i MOD 10 IN sk THEN
        f[r]:=f[0]-f[1]+g[2]-g[1];
      ELSE
        f[r]:=-f[r-1]+g[0]-f[2]-g[r-1];
      END;
      IF i DIV 2 = 0 THEN
        g[r]:=3*f[r-2]+2*(g[2]-f[3])-g[0];
      ELSE
        g[r]:=-g[1]-f[r-2];
      END;
      FOR j:=0 TO r-1 DO
        f[j]:=f[j+1];
    g[j]:=g[j+1];
      END;
    END;
  END;
  RETURN f[r];
END fiter;
(*glavni program*)
VAR n,r:INTEGER;
BEGIN
  REPEAT
    WriteString('Unesite n (0<=n<=');
    WriteInt(maxn,1);
    WriteString('): ');
    ReadInt(n);
  UNTIL (0<=n) AND (n<=maxn);
  REPEAT
    WriteString('Unesite r (6<=r<=');
    WriteInt(maxr,1);
    WriteString('): ');
    ReadInt(r);
  UNTIL (6<=r) AND (r<=maxr);
  WriteString('Frec1(n,r)=');
  WriteInt(frec(n,r),5);
  WriteLn;
  WriteString('Frec2(n,r)=');
  WriteInt(frec2(n,r),5);
  WriteLn;
  WriteString('Fiter(n,r)=');
  WriteInt(fiter(n,r),5);
  WriteLn;
END kolok.