How do I approach Coding & Algorithms interview questions?

Coding & Algorithms questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master coding & algorithms interviews.

What difficulty level is this interview question?

This is a hard difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at Glean.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Glean during technical interviews.

Implement 2048 tilt move | Glean Interview Question

Q: Implement 2048 tilt move

This question evaluates a candidate's ability to implement array and matrix manipulation, deterministic state-transition logic, and rule-based merging behavior in a grid-based simulation.

Problem: Implement a 2048 “tilt” (move) operation

You are given a 4×4 board for the game 2048. Each cell contains either 0 (empty) or a power of two (2, 4, 8, ...). When the player swipes in one of four directions (up, down, left, right), the board updates as follows:

Shift: All non-zero tiles move as far as possible in the swipe direction.
Merge: If two tiles with the same value collide during the move, they merge into one tile with value equal to the sum (i.e., doubled).
Single-merge rule: A tile can be merged at most once per move .
After merges, tiles continue shifting to fill gaps in the swipe direction.

Task

Implement a function that applies exactly one swipe (tilt) to the board.

Function signature (language-agnostic)

Input:
- board : 4×4 integer matrix
- dir : one of {up, down, left, right}
Output:
- The updated 4×4 board after the move

Examples

Swipe left:
- [2, 0, 2, 4] → [4, 4, 0, 0]
Swipe left (single-merge rule):
- [2, 2, 2, 0] → [4, 2, 0, 0] (not [8, 0, 0, 0] )
Swipe left:
- [4, 4, 4, 4] → [8, 8, 0, 0]

Constraints / Notes

Board size is always 4×4.
Only implement the tilt/move logic (no random tile spawning, no scoring required unless you choose to return it as an extra).
Be careful with edge cases around multiple merges in a line and ensuring each tile merges at most once per move.

Problem: Implement a 2048 “tilt” (move) operation

Shift: All non-zero tiles move as far as possible in the swipe direction.

Merge: If two tiles with the same value collide during the move, they merge into one tile with value equal to the sum (i.e., doubled).

Single-merge rule: A tile can be merged at most once per move .

After merges, tiles continue shifting to fill gaps in the swipe direction.

Task

Implement a function that applies exactly one swipe (tilt) to the board.

Function signature (language-agnostic)

Input:

board : 4×4 integer matrix
dir : one of {up, down, left, right}

Output:

The updated 4×4 board after the move

Examples

Swipe left:

[2, 0, 2, 4] → [4, 4, 0, 0]

Swipe left (single-merge rule):

[2, 2, 2, 0] → [4, 2, 0, 0] (not [8, 0, 0, 0] )

Swipe left:

[4, 4, 4, 4] → [8, 8, 0, 0]

Constraints / Notes

Board size is always 4×4.

Only implement the tilt/move logic (no random tile spawning, no scoring required unless you choose to return it as an extra).

Be careful with edge cases around multiple merges in a line and ensuring each tile merges at most once per move.

Implement 2048 tilt move

Quick Overview

Problem: Implement a 2048 “tilt” (move) operation

Task

Function signature (language-agnostic)

Examples

Constraints / Notes

Submit Your Answer to Earn 20XP

Implement 2048 tilt move

Quick Overview

Problem: Implement a 2048 “tilt” (move) operation

Task

Function signature (language-agnostic)

Examples

Constraints / Notes

Submit Your Answer to Earn 20XP