Preparation for live-coding: 15 techniques

# Effective Preparation for Live-Coding Interviews: 15 Practical Tips

Start preparing for live-coding with Easy-level problems on platforms like LeetCode. This reinforces syntax, basic data structures, and common algorithms. Medium and Hard problems require combinations of techniques that can lead to getting stuck without a solid foundation. Sort problems by difficulty and solve them sequentially — this prevents burnout and builds confidence.

Review your solutions: passing once doesn't guarantee success in an interview. Note down time, space, and approaches in the platform's notes. Return in a week — measure your progress.

Analyzing Others' Solutions and Brute Force

Study top solutions after yours: they reveal optimal algorithms and patterns. This trains code reading and expands your toolkit without dry theory.

Solve brute force first — it saves time in interviews. Clean code is nice, but priority is a working solution. Implement first, then optimize. Google syntax, docs, algorithm cheat sheets (not full solutions).

Leveraging Data Structures

Leverage the specifics of types:

• Strings and lists: slicing, reversing, iteration.
• Sets: removing duplicates.
• Dictionaries (hashmap): O(1) lookups, frequencies, indices.

Example frequency count:

def count_letters(sentence: str) -> dict:
    freq = {}
    for letter in sentence:
        if letter not in freq:
            freq[letter] = 1
        else:
            freq[letter] += 1
    return freq

Conversions between types open up efficient paths.

Timing, Notes, and Development Environment

Time yourself for 20–30 minutes per problem — standard interview time. Use the platform's timer or your phone. After solving, note:

• Runtime.
• Algorithms.
• Sticking points.

Solve in an IDE: set up your environment, hotkeys, autocomplete (allowed in interviews). For practice, disable it — trains syntax memorization.

Testing and Debugging

Write 2–3 asserts for verification:

def test_score_of_five():
    assert find_rank(score=[5, 4, 3, 2, 1]) == ["Gold Medal", "Silver Medal", "Bronze Medal", "4", "5"]

def test_score_of_three():
    assert find_rank(score=[5, 4, 3]) == ["Gold Medal", "Silver Medal", "Bronze Medal"]

Debugger shows stack, variable values — crucial for bugs. Alternative — notebook for ideas and docstrings with test cases:

def majority_element(nums: list[int]) -> int:
    """
    Input: nums = [3,2,3]
    Output: 3

    Input: nums = [2,2,1,1,1,2,2]
    Output: 2

    Ogranicheniya:
    1 <= n <= 5 * 10**4"""
    ...

Algorithms and XOR Example

Study topic-specific lists: bits, XOR, pointers. Example single number using XOR:

def single_number(nums: list[int]) -> int:
    xor = 0
    for num in nums:
        xor ^= num  # Dubli skhlopyvayutsya
    return xor

Key Points:

• Start with Easy, review, time 20 min.
• Brute force + refactoring, Google syntax.
• Hashmap for O(1), tests and debugger mandatory.
• Docstrings with cases, disable autocomplete in practice.
• Analyze top solutions, study algorithms by lists.

— Editorial Team