The process took two weeks. I applied online through Stack Overflow. Initially, an HR person emailed me, stating that my profile was selected for the interview process.

First, she confirmed a phone interview. The first round was with HR, who asked several questions:

• My motivation
• My understanding of how Booking.com operates
• How Booking.com monetizes through its website and app
• Suggestions for improving the app

This was essentially an assessment of my overall understanding of Booking.com, gained through its app and booking websites.

Next, there was a standard employment history check.

They asked: "Among the applications you developed so far, which application do you feel is most complex and why?"

After this 30-minute session, she confirmed me for the next round, a technical interview.

She emailed me the details and provided tips for the technical round, suggesting I review HackerRank and LeetCode for coding practices under time pressure.

The email also included a website link and password to proceed with a live coding assignment with the interviewers.

Two days later, I was contacted for the second round by two iOS developers via phone.

They asked about my thoughts on the Booking.com iOS app.

Then, they directed me to the live coding notepad (TitanPad).

There, they pasted questions from Objective-C.

1. Given three arrays like the ones below:

NSArray *a = [1, 3, 4, 5]; NSArray *b = [-1, 3, 0, 9]; NSArray *c = [0, 31, 32, 22, 6];

Find the elements from the three arrays that exist in at least two arrays.

Example: [3, 0]

Because 3 is present in arrays a, b, and c, and 0 is present in arrays b and c.

-(NSArray)find2ElementsAtleastPresentIn2Arrays:(NSArray*)aList b:(NSArray*)bList c:(NSArray*)cList { // -- your code here. }