Software Engineer · Full Journey · Coding

IBM — Software Engineer ✅ Passed

Level: Junior-Level

Round: Full Journey · Type: Coding · Difficulty: 6/10 · Duration: 120 min · Interviewer: Neutral

Topics: String Manipulation, Hash Table, Sliding Window, Frequency Counting

Location: San Francisco Bay Area

Interview date: 2026-01-15

Summary

Round 1: Coding

Question: Given an array of strings, maximize the number of palindromic strings by swapping characters between different strings.

Round 2: Coding

Question: Find the minimum length subarray containing k distinct numbers.

Details

Problem 1: Maximum Palindromes After Swaps

Problem Description: Given an integer n and a string array arr of size n containing lowercase letters. You can perform the following operation any number of times: Choose two different strings and swap one character from each. The goal is to maximize the number of possible palindromic strings in arr after performing the operations.

Example: Input: arr = ["pass", "sas", "asps", "df"] Output: 3

Idea: Fix the length of each string. Characters can be globally allocated. First, calculate character frequencies, then count pairs and singles. Finally, allocate based on length.

Problem 2: Minimum Length Subarray with K Distinct Numbers

Problem Description: Given an integer array and an integer k, find the size of the smallest subarray that contains k distinct integers.

Approach: Use a hashmap to count number frequencies and a sliding window to check for k distinct numbers.