2544. Alternating Digit Sum
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Topics
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
Hints
Hint 1
The first step is to loop over the digits. We can convert the integer into a string, an array of digits, or just loop over its digits.
Hint 2
Keep a variable sign that initially equals 1 and a variable answer that initially equals 0.
Hint 3
Each time you loop over a digit i, add sign * i to answer, then multiply sign by -1.