String Compression — Medium Coding Interview Question

Given an array of characters chars, compress it in-place using the following algorithm: Begin with an empty string s. For each group of consecutive repeating characters in chars: if length is 1, append the char; if length > 1, append char followed by length. Return the new length.

Example

Input: chars = ["a","a","b","b","c","c","c"]

Output: 6

Explanation: Compressed to ["a","2","b","2","c","3"]

Constraints

• 1 ≤ chars.length ≤ 2000

Topics & Companies

Topics: strings, two-pointers

Asked by: Amazon, Google, Microsoft, Meta

Optimal Solution Complexity

Time complexity: O(n). Space complexity: O(1).

Practice more

• All DSA Problems
• DSA Patterns