Practice Your Skills
Sharpen your coding skills with hundreds of algorithm problems to practice.
Problem 1: Two Sum
Given an array of integers, return indices of the two numbers such that they add up to a specific target.
Problem 2: Longest Substring Without Repeating Characters
Find the length of the longest substring without repeating characters.
Problem 2: Add Two Numbers
You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order.
Problem 4: Median of Two Sorted Arrays
Given two sorted arrays, find the median of the two sorted arrays.
Problem 5: Longest Palindromic Substring
Given a string, find the longest palindromic substring in it.
Problem 6: Zigzag Conversion
Convert a string to a zigzag pattern on a given number of rows and read line by line.
Problem 7: Reverse Integer
Given a 32-bit signed integer, reverse its digits.
Problem 8: String to Integer (atoi)
Implement the `atoi` function, which converts a string to an integer.
Problem 9: Palindrome Number
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
Problem 10: Regular Expression Matching
Implement regular expression matching with support for `.` and `*`.
Problem 11: Rotate List
Given the head of a linked list and an integer k, rotate the list to the right by k places.