program FlipNumbers;
{
Six different functions that accept 5 or 7
and return the other number, without using if/switch.
}
uses
Math; { for Abs() }
{ 1. Arithmetic sum trick: 5 + 7 = 12 }
function FlipSum(x: Integer): Integer;
begin
FlipSum := 12 - x;
end;
{ 2. Product trick: 5 * 7 = 35 }
function FlipProduct(x: Integer): Integer;
begin
FlipProduct := 35 div x;
end;
{ 3. XOR trick: 5 xor 7 = 2
x xor 2 flips 5 ↔ 7 }
function FlipXor(x: Integer): Integer;
begin
FlipXor := x xor 2;
end;
{ 4. Modulo-based trick using divisibility:
x mod 7 = 0 → x is 7
x mod 5 = 0 → x is 5
Boolean expressions evaluate to 0 or 1 in arithmetic. }
function FlipMod(x: Integer): Integer;
begin
FlipMod := 5 * Ord(x mod 7 = 0) + 7 * Ord(x mod 5 = 0);
end;
{ 5. Absolute-value trick: |x - 12| flips 5 ↔ 7 }
function FlipAbs(x: Integer): Integer;
begin
FlipAbs := Abs(x - 12);
end;
{ 6. Array lookup using boolean indexing }
function FlipArray(x: Integer): Integer;
const
Table: array[0..1] of Integer = (7, 5);
begin
{ x = 5 → (x = 5) = TRUE → Ord(TRUE) = 1 → Table[1] = 5
x = 7 → (x = 5) = FALSE → Ord(FALSE) = 0 → Table[0] = 7 }
FlipArray := Table[Ord(x = 5)];
end;
begin
Writeln('flip_sum(5) = ', FlipSum(5));
Writeln('flip_sum(7) = ', FlipSum(7));
Writeln;
Writeln('flip_product(5) = ', FlipProduct(5));
Writeln('flip_product(7) = ', FlipProduct(7));
Writeln;
Writeln('flip_xor(5) = ', FlipXor(5));
Writeln('flip_xor(7) = ', FlipXor(7));
Writeln;
Writeln('flip_mod(5) = ', FlipMod(5));
Writeln('flip_mod(7) = ', FlipMod(7));
Writeln;
Writeln('flip_abs(5) = ', FlipAbs(5));
Writeln('flip_abs(7) = ', FlipAbs(7));
Writeln;
Writeln('flip_array(5) = ', FlipArray(5));
Writeln('flip_array(7) = ', FlipArray(7));
end.
{
OUTPUT:
flip_sum(5) = 7
flip_sum(7) = 5
flip_product(5) = 7
flip_product(7) = 5
flip_xor(5) = 7
flip_xor(7) = 5
flip_mod(5) = 7
flip_mod(7) = 5
flip_abs(5) = 7
flip_abs(7) = 5
flip_array(5) = 5
flip_array(7) = 7
}
