LeetCode 3490: Count Beautiful Numbers Solution

Master LeetCode problem 3490 (Count Beautiful Numbers), a hard challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

3490. Count Beautiful Numbers

Hard

Dynamic Programming

Problem Explanation

Explanation:

To solve this problem, we can iterate through each number from l to r (inclusive), calculate the product and sum of its digits, and check if the product is divisible by the sum. If it is, then the number is considered beautiful and we increment the count.

Algorithm:

Define a helper function to calculate the product of digits.
Define a helper function to calculate the sum of digits.
Initialize a variable count to 0.
Iterate through each number from l to r.
For each number, calculate the product and sum of its digits.
If the product is divisible by the sum, increment the count.
Return the count as the result.

Time Complexity: O((r-l) * log(r)) Space Complexity: O(1)

Solution Code

class Solution {
    public int countBeautifulNumbers(int l, int r) {
        int count = 0;
        for (int i = l; i <= r; i++) {
            int product = getProductOfDigits(i);
            int sum = getSumOfDigits(i);
            if (product % sum == 0) {
                count++;
            }
        }
        return count;
    }
    
    private int getProductOfDigits(int num) {
        int product = 1;
        while (num > 0) {
            product *= num % 10;
            num /= 10;
        }
        return product;
    }
    
    private int getSumOfDigits(int num) {
        int sum = 0;
        while (num > 0) {
            sum += num % 10;
            num /= 10;
        }
        return sum;
    }
}

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