## Problem A password was encoded with the following steps applied in order: 1. Reverse the string. 2. Replace each letter with the letter `k` positions forward in the alphabet (wrapping: z+1=a). `k` is given. 3. Swap each pair of adjacent characters (swap index 0-1, 2-3, etc.; if odd length, last char stays). Given the encoded string and `k`, return the original password. ```python def decode_password(encoded: str, k: int) -> str: ... ``` ``` Original: "hello" Step 1 (reverse): "olleh" Step 2 (shift +2): "qnnhj" Step 3 (swap pairs): "nqnjh" Encoded: "nqnjh" decode_password("nqnjh", 2) -> "hello" ``` ## Follow-ups 1. Walk through each decode step in reverse order. What is the inverse of each operation? 2. What edge cases matter: `k=0`, `k=26`, an empty string, non-letter characters? 3. If the encoding scheme had 10 steps, how would you structure your decoder to make it easy to add/remove steps? 4. This encoding is symmetric for step 3 (swap is its own inverse). How does that simplify your decode logic?

InterviewDB Experience

Decode Password: Reverse a Multi-Step Encoding Scheme to Recover the Original Password

phone

Interview Experience

Problem A password was encoded with the following steps applied in order: Reverse the string. Replace each letter with the letter k positions forward in the alphabet (wrapping: z+1=a). k is given. Swap each pair of adjacent characters (swap index 0-1, 2-3, etc.; if odd length, last char stays). Given the encoded string and k, return the original password. Follow-ups Walk through each decode step in reverse order. What is the inverse of each operation? What edge cases matter: k=0, k=26, an empty…

Full Details

🔒

Unlock all Instacart questions

Full insider details, leaked discussions, and candidate experiences.

or every company, $100/year →

About This Question

This is a candidate experience report from a instacart interview during the phone round.

It covers the following topics: Coding, Phone, Onsite, Strings .

Topics

Coding Phone Onsite Strings

Decode Password: Reverse a Multi-Step Encoding Scheme to Recover the Original Password

Interview Experience

Full Details

About This Question

Topics

More Instacart Interview Questions