Question

How to multiply two numbers recursively without using multiplication, division, bitwise and loops in Rust

Answer 1

fn multiply(x : i32, y : i32) -> i32 {
    if y > 0 {
        return x + multiply(x, y - 1);
    }
    if y < 0 {
        return -multiply(x, -y);
    }
    return 0;
}
    
fn main() {
    println!("3 * 7 = {}", multiply(3, 7));
    println!("3 * 0 = {}", multiply(3, 0));
    println!("0 * 3 = {}", multiply(0, 3));
    println!("3 * -5 = {}", multiply(3, -5));
    println!("-3 * 6 = {}", multiply(-3, 6));
}



/*
run:

3 * 7 = 21
3 * 0 = 0
0 * 3 = 0
3 * -5 = -15
-3 * 6 = -18

*/

 

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