Meta E5 || London
- Location
- London
- Posted
- 23 Oct 2025
Summary
I recently interviewed for an E5 role at Meta in London, which consisted of a comprehensive loop including a screening round, two data structures and algorithms rounds, a behavioral round, and a system design round. I encountered a variety of challenging problems ranging from merging sorted arrays to designing a messaging service like WhatsApp.
How it went
Screening Round
My interview process began with a screening round, which featured two questions that I would classify as easy to medium difficulty.
Full Loop Interviews
Following the screening, I moved on to the full loop, which was structured as follows:
1. Behavioral Round
This round focused on my past experiences and how I handled various situations, typical of a behavioral interview.
2. DSA Round 1
In the first data structures and algorithms round, I was presented with two problems:
- One involved determining if a matrix represented as an array was a Toeplitz matrix.
- The other was a problem similar to finding the maximum consecutive ones with some allowed flips.
3. DSA Round 2
The second DSA round also had two questions:
- The first asked me to remove extra parentheses to make a string valid.
- The second was about finding the shortest path in a 1-0 matrix from the top-left to the bottom-right corner.
4. Design Round
The final round was a system design interview where I was asked to design WhatsApp, specifically emphasizing the use of API calls instead of websockets for communication.
Questions asked (6)
- 01
Random Pick with Weight
Data Structures & Algorithms · Medium
Open the problemYou are given an array of positive integers w, where w[i] describes the weight of the ith index. Implement the function pickIndex() which randomly picks an index in proportion to its weight.
- 02
Toeplitz Matrix Check (Array Form)
Data Structures & Algorithms · Easy
Given an array, determine if it represents a Toeplitz matrix. A matrix is Toeplitz if every diagonal from top-left to bottom-right has the same elements.
- 03
Max Consecutive Ones with Flips (Similar)
Data Structures & Algorithms · Medium
A problem similar to finding the maximum number of consecutive ones in a binary array, potentially allowing a certain number of zero flips.
- 04
Minimum Remove to Make Valid Parentheses
Data Structures & Algorithms · Medium
Given a string s of '(' , ')' and lowercase English characters, remove the minimum number of parentheses ( '(' or ')') so that the resulting parentheses string is valid. Return any valid string.
- 05
Shortest Path in Binary Matrix
Data Structures & Algorithms · Medium
Given an n x n binary matrix grid, return the length of the shortest clear path in the matrix. A clear path is a path from the top-left cell (0, 0) to the bottom-right cell (n - 1, n - 1) such that all visited cells are 0 and all adjacent cells in the path are 8-directionally connected.
- 06
Design WhatsApp (API calls only)
System Design · Hard
Design a system similar to WhatsApp, focusing on using API calls for communication rather than websockets.