Alternating Digit Sum

Problem Statement - link #

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.

Examples #

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 <= 10^9

Solutions #

class Solution {
    public int alternateDigitSum(int n) {
       int sum = 0;
        int sign = 1;
        String str = Integer.toString(n);
        for(char c: str.toCharArray()) {
            sum += (c - '0') * (sign);
            sign *= -1;
        }
        return sum;
    }
}