Microsoft

"Given an array of integers, find the contiguous subarray with the largest sum": The interviewer asked for an O(N) solution without nested loops; I solved it using Kadane’s Algorithm, maintaining a running current sum that resets to 0 whenever it turns negative while updating the global maximum sum at each step. "Detect if a singly linked list contains a cycle without modifying node values or using extra memory": The panel barred hash sets to enforce O(1) auxiliary space; I implemented Floyd’s Cycle-Finding Algorithm (Fast & Slow Pointers), advancing one pointer by one step and the other by two steps until they either collide or hit the null tail. "Given a string of opening and closing brackets, determine if the input sequence is valid and properly balanced": The interviewer challenged me to verify nesting order in a single pass; I solved it using a Stack, pushing expected closing matches for each opening bracket and validating that every closing bracket matches the top element before popping it off.