README.md

2544. Alternating Digit Sum

You are given a positive integer n. Each digit of n has a sign according to the following rules:

• The most significant digit is assigned a positive sign.
• Each other digit has an opposite sign to its adjacent digits.

Return the sum of all digits with their corresponding sign.

Example 1:

Input: n = 521
Output: 4
Explanation: (+5) + (-2) + (+1) = 4.

Example 2:

Input: n = 111
Output: 1
Explanation: (+1) + (-1) + (+1) = 1.

Example 3:

Input: n = 886996
Output: 0
Explanation: (+8) + (-8) + (+6) + (-9) + (+9) + (-6) = 0.

Constraints:

• 1 <= n <= 109

Solutions (Rust)

1. Solution

impl Solution {
    pub fn alternate_digit_sum(n: i32) -> i32 {
        let mut n = n;
        let mut ret = 0;

        while n > 0 {
            ret = n % 10 - ret;
            n /= 10;
        }

        ret
    }
}