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 easy difficulty Coding & Algorithms question, commonly asked during Onsite rounds at Google.

What role is this question designed for?

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

Solve three coding problems | Google Interview Question

Quick Overview

This set of problems evaluates algorithmic problem-solving across combinatorics and enumeration (finding the N-th lexicographic license plate), constrained geometric and graph traversal reasoning (counting Android-style 3x3 unlock patterns), and interval-processing algorithms (computing intersections of sorted, non-overlapping intervals) within the domain of algorithms and data structures. These questions are commonly asked because they reveal ability to reason about discrete enumeration, constraint handling, and efficient time/space implementations for edge-case-heavy inputs, and the level of abstraction spans both conceptual understanding (combinatorial and geometric constraints) and practical application (efficient algorithm and data-structure implementation).

The interview note described the following coding questions:

Find the N-th license plate in lexicographic order
- A license plate has exactly 6 characters: the first 3 are uppercase letters A-Z , and the last 3 are digits 0-9 .
- Example format: AAA000 .
- Consider all valid license plates sorted in lexicographic order as strings.
- Given an integer N (1-indexed), return the N -th license plate.
Count Android-style 3x3 unlock patterns
- You have a 3x3 grid of dots, like the standard Android lock screen.
- A valid pattern is a sequence of distinct dots.
- Moving from one dot to another is allowed unless the straight line between them passes through another dot that has not been visited yet.
- Count the total number of valid unlock patterns that use between 4 and 9 dots, inclusive.
Return intersections of two interval lists
- You are given two lists of closed intervals.
- Within each list, intervals are sorted by start time and do not overlap with each other.
- Return all intervals where the two lists overlap.

Solve three coding problems

Quick Overview

Solve three coding problems

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