Solve the Easy-level Longest Common Prefix coding interview problem online in Python & JavaScript. Run your code against real test cases in the browser and study worked examples. It covers strings. Read the step-by-step solution and complexity analysis. Java starter code is also included for reference (no in-browser JVM yet, so it can't be run here).

Longest Common Prefix – Solve Online in Python & JavaScript

Find the longest common prefix string amongst an array of strings.

Given an array of strings, find the longest common prefix string amongst them. If there is no common prefix, return an empty string "".


Note:

All given inputs are in lowercase letters a-z.

- Given an array of strings, find the longest common prefix among all strings.
- If no common prefix exists, return an empty string `""`.

Understanding the Problem

- Before proceeding, handle cases where the input list is empty or contains only one string.
  - If the list is empty, return an empty string.
  - If the list has only one string, return that string as the common prefix.

Handle Edge Cases

- Start by assuming the entire first string in the array is the longest common prefix.
- We’ll trim this prefix as we compare it to other strings in the array.

Initialize the First String as a Reference Prefix

- Loop through each string in the array (starting from the second string).
- For each string, compare characters with the current `prefix` and shorten `prefix` if characters don’t match.

Iterate Over Each String and Adjust the Prefix

- After iterating through all strings and adjusting the prefix, return the final value of `prefix`.
- This value represents the longest common prefix shared by all strings in the array.

Return the Final Prefix

- Edge cases include:
  - An array with an empty string, which results in an empty prefix.
  - No common prefix across strings, which should return an empty string.
  - All strings being identical, in which case the common prefix is the string itself.