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

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This question is commonly asked for Site Reliability Engineer candidates at Bytedance during technical interviews.

Generate combinations and permutations | Bytedance Coding Question

Quick Overview

This question evaluates a candidate's ability to implement combinatorial generation of combinations and permutations using distinct elements, testing understanding of combinatorics, search-space enumeration, and uniqueness constraints within the Coding & Algorithms domain.

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Quick Overview

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Bytedance
Coding & Algorithms
Site Reliability Engineer

Generate combinations and permutations

Company: Bytedance

Role: Site Reliability Engineer

Category: Coding & Algorithms

Difficulty: medium

Interview Round: Technical Screen

Given two integers n and k, where 1 <= k <= n, write code for two related tasks using the numbers 1 through n: 1. Generate all unique combinations of size k. 2. Generate all unique ordered arrangements of length k using distinct numbers. A number may not be reused within the same result, and the output must not contain duplicate sequences. Explain the approach and analyze the time and space complexity.

Quick Answer: This question evaluates a candidate's ability to implement combinatorial generation of combinations and permutations using distinct elements, testing understanding of combinatorics, search-space enumeration, and uniqueness constraints within the Coding & Algorithms domain.

Generate Combinations

Return all size-k combinations from numbers 1..n in lexicographic order.

Constraints

Inputs are Python literals matching the function signature.
Return a deterministic exact-match value.

Examples

Input: (4,2)

Expected Output: [[1, 2], [1, 3], [1, 4], [2, 3], [2, 4], [3, 4]]

Explanation: All 2-combinations from 1..4.

Input: (3,3)

Expected Output: [[1, 2, 3]]

Explanation: Only one full-size combination.

Hints

Clarify edge cases before coding.
Keep the return value deterministic.

Generate Length-K Permutations

Return all ordered length-k arrangements from numbers 1..n without reuse.

Constraints

Inputs are Python literals matching the function signature.
Return a deterministic exact-match value.

Examples

Input: (3,2)

Expected Output: [[1, 2], [1, 3], [2, 1], [2, 3], [3, 1], [3, 2]]

Explanation: All length-2 permutations from 1..3.

Input: (2,2)

Expected Output: [[1, 2], [2, 1]]

Explanation: Both full permutations.

Hints

Clarify edge cases before coding.
Keep the return value deterministic.

Last updated: Jun 27, 2026