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

Solve Three Coding Problems | Snapchat Interview Question

Quick Overview

This set of problems evaluates competencies in streaming data handling and incremental aggregation, time-dependent grid traversal and reachability under dynamic hazards, and planar path existence with geometric obstacles, touching on data structures, graph algorithms, and computational geometry within the Coding & Algorithms domain.

The interview included three coding problems:

Streaming top-k class. Design a class for an integer stream with a fixed parameter k . It should support add(x) to ingest a new value and getTopK() to return the k largest values seen so far in descending order. If fewer than k values have appeared, return all of them. Aim for efficient incremental updates.
Maximum safe delay in a burning grid. You are given an m x n grid containing empty cells, walls, and initial fire sources. Fire spreads every minute to the four neighboring non-wall cells. A person starts at the top-left cell and wants to reach the bottom-right cell. Before moving, the person may wait for t minutes at the start, then moves one step per minute through non-wall cells. The person may never enter a cell after the fire has arrived there; arriving at the destination at the same minute as the fire is allowed. Return the maximum t that still allows escape, return -1 if escape is impossible even with no waiting, and return 1000000000 if escape is possible for arbitrarily large t .
Reachability in a rectangle with circular blockers. You are given a rectangle with corners (0, 0) and (X, Y) , along with several closed circles inside or touching the rectangle. Determine whether there exists a continuous path from (0, 0) to (X, Y) that stays within the rectangle and never touches or enters any circle. The path may move in any direction.

Quick Overview

The interview included three coding problems:

Streaming top-k class. Design a class for an integer stream with a fixed parameter k . It should support add(x) to ingest a new value and getTopK() to return the k largest values seen so far in descending order. If fewer than k values have appeared, return all of them. Aim for efficient incremental updates.
Maximum safe delay in a burning grid. You are given an m x n grid containing empty cells, walls, and initial fire sources. Fire spreads every minute to the four neighboring non-wall cells. A person starts at the top-left cell and wants to reach the bottom-right cell. Before moving, the person may wait for t minutes at the start, then moves one step per minute through non-wall cells. The person may never enter a cell after the fire has arrived there; arriving at the destination at the same minute as the fire is allowed. Return the maximum t that still allows escape, return -1 if escape is impossible even with no waiting, and return 1000000000 if escape is possible for arbitrarily large t .
Reachability in a rectangle with circular blockers. You are given a rectangle with corners (0, 0) and (X, Y) , along with several closed circles inside or touching the rectangle. Determine whether there exists a continuous path from (0, 0) to (X, Y) that stays within the rectangle and never touches or enters any circle. The path may move in any direction.

Solve Three Coding Problems

Quick Overview

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Solve Three Coding Problems

Quick Overview

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