LeetCode 1281: Subtract the Product and Sum of Digits of an Integer

Meta Data

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Difficulty: easy First Attempt: 2025-12-23

• Submissions: Accepted (C++, first try)

Approach

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Walk every digit, multiplying into a product that starts at 1 and adding into a sum that starts at 0, then return product - sum.

My Solution

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I used C++ to_string to walk the digits; here is the equivalent Python:

class Solution:
    def subtractProductAndSum(self, n: int) -> int:
        product, total = 1, 0
        while n:
            d = n % 10
            product *= d
            total += d
            n //= 10
        return product - total

Complexity

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Time O(d), space O(1).

Mistakes to Avoid

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• The product starts at 1, not 0.

Interview Explanation

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Peel digits with % 10, accumulating the product and sum together, then subtract. Time O(d).