## Problem Given four single-digit integers, insert `+`, `-`, `*`, `/` between them (in any order, using each digit exactly once) to reach a target value. Return all distinct valid expressions. You may also use parentheses to change evaluation order. ```python def four_digits( digits: list[int], # exactly 4 digits target: int ) -> list[str]: # list of valid expression strings pass ``` ## Example ``` Input: digits=[1, 2, 3, 4], target=24 Sample valid outputs: "1 * 2 * 3 * 4" -> 24 "(1 + 2 + 3) * 4" -> 24 "(2 + 3 - 1) * 4" -> 16 (invalid) Output: ["1 * 2 * 3 * 4", "(1 + 2 + 3) * 4", ...] ``` ## Follow-ups 1. How many distinct expression trees are possible with 4 operands and 4 operators? Enumerate the cases. 2. How do you handle division by zero safely? 3. For which sets of 4 digits is it impossible to reach 24? 4. How does complexity scale if extended to `n` digits?

InterviewDB Experience

Four Digits: Find All Valid Arithmetic Expressions from Four Single Digits

Interview Experience

Problem Given four single-digit integers, insert +, -, *, / between them (in any order, using each digit exactly once) to reach a target value. Return all distinct valid expressions. You may also use parentheses to change evaluation order. Example Follow-ups How many distinct expression trees are possible with 4 operands and 4 operators? Enumerate the cases. How do you handle division by zero safely? For which sets of 4 digits is it impossible to reach 24? How does complexity scale if extended t…

Full Details

🔒

Unlock all Shopify questions

Full insider details, leaked discussions, and candidate experiences.

Get full access — $100 a year, unlimited access

About This Question

This is a candidate experience report from a shopify interview.

It covers the following topics: Coding, Pair Programming, Strings .

Topics

Coding Pair Programming Strings

Four Digits: Find All Valid Arithmetic Expressions from Four Single Digits

Interview Experience

Full Details

About This Question

Topics

More Shopify Interview Questions