Twitter (X) Coding Questions 2025-2026 | Placement Interview Problems with Solutions

Twitter (X) coding rounds assess DSA and problem-solving at a high bar for real-time and scale-oriented engineering. The process typically includes an online coding round (e.g. 60–90 minutes) with 3–4 problems (medium to hard) and technical interviews with DSA, system design, and deep dives. They test arrays, strings, trees, graphs, DP, and optimal solutions; communication and complexity analysis matter.

Twitter (X) Coding Round at a Glance

Format: OA with 3–4 coding problems; technical rounds with DSA and system design. Difficulty: Medium to hard. Topics: Arrays, strings, trees, graphs, DP, system design. Focus: Optimal solutions, complexity, and communication.

Coding Questions - Complete Problem Set

Practice coding interview questions with solutions.

Arrays & Strings

1. Two Sum

def two_sum(nums, target):
    seen = {}
    for i, num in enumerate(nums):
        if target - num in seen:
            return [seen[target - num], i]
        seen[num] = i
    return []

2. Valid Parentheses

def is_valid(s):
    stack = []
    mapping = {')': '(', '}': '{', ']': '['}
    for char in s:
        if char in mapping:
            top = stack.pop() if stack else '#'
            if mapping[char] != top:
                return False
        else:
            stack.append(char)
    return not stack

3. Reverse String

def reverse_string(s):
    return s[::-1]

4. Palindrome Check

def is_palindrome(s):
    s = ''.join(c.lower() for c in s if c.isalnum())
    return s == s[::-1]

5. Merge Intervals

def merge(intervals):
    intervals.sort(key=lambda x: x[0])
    merged = []
    for interval in intervals:
        if not merged or merged[-1][1] < interval[0]:
            merged.append(interval)
        else:
            merged[-1][1] = max(merged[-1][1], interval[1])
    return merged

6. Maximum Subarray

def max_subarray(nums):
    max_sum = current_sum = nums[0]
    for num in nums[1:]:
        current_sum = max(num, current_sum + num)
        max_sum = max(max_sum, current_sum)
    return max_sum

7. LRU Cache

from collections import OrderedDict

class LRUCache:
    def __init__(self, capacity):
        self.cache = OrderedDict()
        self.capacity = capacity

    def get(self, key):
        if key not in self.cache:
            return -1
        self.cache.move_to_end(key)
        return self.cache[key]

    def put(self, key, value):
        if key in self.cache:
            self.cache.move_to_end(key)
        self.cache[key] = value
        if len(self.cache) > self.capacity:
            self.cache.popitem(last=False)

Company-Specific Focus Areas

Twitter (X) often emphasizes arrays and strings (sliding window, parsing, optimization), trees and graphs (BFS/DFS, shortest path, traversal), dynamic programming, hash-based structures, and system design (feed, rate limiting, scale) in later rounds. Focus on optimal time/space complexity and clear explanation; real-time and scale are recurring themes.

Related Resources

Interview Experience

Real interview experiences.

Preparation Guide

Complete preparation strategy.

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Practice these problems and focus on DSA, optimal solutions, and system design for Twitter (X) interviews.

Last updated: February 2026