/*
Six different functions that accept 5 or 7
and return the other number, without using if/switch.
*/
// 1. Arithmetic sum trick: 5 + 7 = 12
fn flip_sum(x: i32) -> i32 {
12 - x
}
// 2. Product trick: 5 * 7 = 35
fn flip_product(x: i32) -> i32 {
35 / x
}
// 3. XOR trick: 5 ^ 7 = 2
// x ^ 2 flips 5 ↔ 7
fn flip_xor(x: i32) -> i32 {
x ^ 2
}
// 4. Modulo-based trick using divisibility:
// x % 7 == 0 → x is 7
// x % 5 == 0 → x is 5
// Boolean → integer via as i32
fn flip_mod(x: i32) -> i32 {
5 * ((x % 7 == 0) as i32)
+ 7 * ((x % 5 == 0) as i32)
}
// 5. Absolute-value trick: |x - 12| flips 5 ↔ 7
fn flip_abs(x: i32) -> i32 {
(x - 12).abs()
}
// 6. Array lookup using arithmetic index:
// For x = 5 → (5 - 5) / 2 = 0 → table[0] = 7
// For x = 7 → (7 - 5) / 2 = 1 → table[1] = 5
fn flip_array(x: i32) -> i32 {
let table = [7, 5];
let index = (x - 5) / 2;
table[index as usize]
}
fn main() {
println!("flip_sum(5) = {}", flip_sum(5));
println!("flip_sum(7) = {}", flip_sum(7));
println!();
println!("flip_product(5) = {}", flip_product(5));
println!("flip_product(7) = {}", flip_product(7));
println!();
println!("flip_xor(5) = {}", flip_xor(5));
println!("flip_xor(7) = {}", flip_xor(7));
println!();
println!("flip_mod(5) = {}", flip_mod(5));
println!("flip_mod(7) = {}", flip_mod(7));
println!();
println!("flip_abs(5) = {}", flip_abs(5));
println!("flip_abs(7) = {}", flip_abs(7));
println!();
println!("flip_array(5) = {}", flip_array(5));
println!("flip_array(7) = {}", flip_array(7));
}
/*
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) = 7
flip_array(7) = 5
*/
