Find the longest leading substring shared by every string in a list. Test your code, then compare with the explained solution. Free online practice.

Longest Common Prefix – Solve Online

Palindrome String

Reverse a String

Find the longest leading substring shared by every string in a list.

Given an array of strings, return the longest prefix shared by every string. Return an empty string when the list is empty or no common prefix exists.

**Input / output**
- Input: `strs: string[]`
- Output: common prefix string

**Examples**
1. `["flower", "flow", "flight"]` returns `"fl"`.
2. `["dog", "racecar", "car"]` returns `""`.

**Constraints**
- `0 <= strs.length <= 200`
- `0 <= strs[i].length <= 200`
- Comparisons are case-sensitive.

**Follow-up**
Compare horizontal scanning with sorting and a trie. Which is best when queries repeat over a fixed corpus?

- 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.