L-5 at Google

How it went

What they would tell you

How to prepare

Round by round

1. 1

   Technical Coding Round 145 min

   The problem was about finding the earliest time when all people in a network became connected, given a series of logs showing interactions. I first processed the log and counted all the unique people, assigning each person a unique index to build the graph. In my first approach, I treated each person as a separate group. While going through the log, I connected people and decreased the total number of groups. When there was only one group left, I returned that timestamp. Then, I tried a cleaner approach using Union-Find. I made each person their own parent at first, and as I merged groups while going through the logs, I kept track of the number of groups. The moment there was only one group left, I returned the timestamp.

   • Network Connectivity Timestamp
2. 2

   Technical Coding Round 260 min

   Problem: Given a large 2D matrix of integers where each row and each column is sorted in ascending order, implement a function to efficiently determine if a target number exists in the matrix. Matrix: [ [1, 4, 7, 11], [2, 5, 8, 12], [3, 6, 9, 16], [10,13, 14, 17] ] Target: 5 - Output: True Target: 15 - Output: False

   • I approached this problem by starting from the top-right corner of the matrix.
   • If the current number equals the target, return true.
   • If the number is greater than the target, move left.
   • If the number is smaller than the target, move down.
   • This ensured O(m+n) time complexity instead of searching the entire matrix.
   • Matrix Target Search

What came up