public class FlipNumbers {
// Six different functions that accept 5 or 7
// and return the other number, without using if/switch.
// 1. Arithmetic sum trick: 5 + 7 = 12
static int flipSum(int x) {
return 12 - x;
}
// 2. Product trick: 5 * 7 = 35
static int flipProduct(int x) {
return 35 / x;
}
// 3. XOR trick: 5 ^ 7 = 2
// x ^ 2 flips 5 ↔ 7
static int flipXor(int x) {
return x ^ 2;
}
// 4. Modulo-based trick using divisibility:
// x % 7 == 0 → x is 7
// x % 5 == 0 → x is 5
// Boolean expressions become 1 or 0 when used in arithmetic.
static int flipMod(int x) {
return 5 * (x % 7 == 0 ? 1 : 0)
+ 7 * (x % 5 == 0 ? 1 : 0);
}
// 5. Absolute-value trick: |x - 12| flips 5 ↔ 7
static int flipAbs(int x) {
return Math.abs(x - 12);
}
// 6. Array lookup using boolean indexing
static int flipArray(int x) {
int[] table = {7, 5};
return table[(x == 5) ? 1 : 0];
}
public static void main(String[] args) {
System.out.println("flip_sum(5) = " + flipSum(5));
System.out.println("flip_sum(7) = " + flipSum(7));
System.out.println();
System.out.println("flip_product(5) = " + flipProduct(5));
System.out.println("flip_product(7) = " + flipProduct(7));
System.out.println();
System.out.println("flip_xor(5) = " + flipXor(5));
System.out.println("flip_xor(7) = " + flipXor(7));
System.out.println();
System.out.println("flip_mod(5) = " + flipMod(5));
System.out.println("flip_mod(7) = " + flipMod(7));
System.out.println();
System.out.println("flip_abs(5) = " + flipAbs(5));
System.out.println("flip_abs(7) = " + flipAbs(7));
System.out.println();
System.out.println("flip_array(5) = " + flipArray(5));
System.out.println("flip_array(7) = " + flipArray(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) = 5
flip_array(7) = 7
*/
