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2630. Alternating Digit Sum

Easy
Math
Solve on LeetCode View Solutions

Description

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.

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