1281. Subtract the Product and Sum of Digits of an Integer

Input: n = 234
Output: 15 
Explanation: 
Product of digits = 2 * 3 * 4 = 24 
Sum of digits = 2 + 3 + 4 = 9 
Result = 24 - 9 = 15

Input: n = 4421
Output: 21
Explanation: 
Product of digits = 4 * 4 * 2 * 1 = 32 
Sum of digits = 4 + 4 + 2 + 1 = 11 
Result = 32 - 11 = 21

Rust Solution

struct Solution;

impl Solution {
    fn subtract_product_and_sum(mut n: i32) -> i32 {
        let mut product = 1;
        let mut sum = 0;
        while n != 0 {
            let d = n % 10;
            product *= d;
            sum += d;
            n /= 10;
        }
        product - sum
    }
}

#[test]
fn test() {
    assert_eq!(Solution::subtract_product_and_sum(234), 15);
}