Is Concatenate Non-Zero Digits and Multiply by Sum I easy or hard?

Concatenate Non-Zero Digits and Multiply by Sum I is categorized as an Easy problem. It mainly tests basic digit processing, arithmetic manipulation, and careful implementation rather than advanced algorithms.

Concatenate Non-Zero Digits and Multiply by Sum I Python/Java solution

The solution in Python or Java typically loops through each digit, updates the digit sum, and appends non-zero digits to a running integer using multiplication by 10. The final step multiplies the constructed number by the total digit sum. The same logic works in C++, Go, and TypeScript.

How to solve Concatenate Non-Zero Digits and Multiply by Sum I in O(n)?

Traverse the digits of the number once. Maintain two variables: the running sum of digits and a concatenated value formed only from non-zero digits using concat = concat * 10 + digit. After processing all digits, multiply the concatenated number by the digit sum. This ensures linear time with constant extra space.

What is the best approach for Concatenate Non-Zero Digits and Multiply by Sum I?

The best approach is a single-pass simulation over the digits. Track the digit sum while building another number that concatenates only non-zero digits using arithmetic operations. This solution runs in O(n) time with O(1) space, where n is the number of digits.

Is Concatenate Non-Zero Digits and Multiply by Sum I asked at Google/Amazon/Meta?

Problems like this appear in coding interviews as warm-up or screening questions focused on math and simulation. Large companies such as Google, Amazon, and Meta frequently include similar digit-manipulation tasks to test careful implementation and edge-case handling.

What data structure is used in Concatenate Non-Zero Digits and Multiply by Sum I?

No advanced data structure is required. The solution relies on simple arithmetic operations and integer variables to track the digit sum and the concatenated result. Some implementations may temporarily use strings, but the optimal version works entirely with integers.

What is the time complexity of Concatenate Non-Zero Digits and Multiply by Sum I?

The time complexity is O(n) because each digit of the number is processed exactly once. The space complexity can be O(1) when using arithmetic concatenation, or O(n) if a temporary string is used to collect non-zero digits.

3754. Concatenate Non-Zero Digits and Multiply by Sum I - Practice Online

You are given an integer n.

Form a new integer x by concatenating all the non-zero digits of n in their original order. If there are no non-zero digits, x = 0.

Let sum be the sum of digits in x.

Return an integer representing the value of x * sum.

Example 1:

Input: n = 10203004

Output: 12340

Explanation:

The non-zero digits are 1, 2, 3, and 4. Thus, x = 1234.
The sum of digits is sum = 1 + 2 + 3 + 4 = 10.
Therefore, the answer is x * sum = 1234 * 10 = 12340.

Example 2:

Input: n = 1000

Output: 1

Explanation:

The non-zero digit is 1, so x = 1 and sum = 1.
Therefore, the answer is x * sum = 1 * 1 = 1.

Constraints:

0 <= n <= 10⁹