Coding interview problems

Two Sum: finding two numbers in an array that add up to a given target number

Given a collection of intervals, merge any overlapping intervals.

reverse a string interview question

Find the longest common prefix string amongst an array of strings.

Palindrome String: Free. No login required. Python technical interview question

Count how many substrings of a string are palindromes.

Find the longest contiguous substring that is a palindrome.

Check whether the values of a singly linked list form a palindrome.

Given a Roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.

Write a function to generate all possible combinations of letters that can be formed from a given string of digits representing a phone number.

valid parentheses coding question

Learn how to find the index of the first occurrence of a substring in a string in this coding interview problem.

Find the length of the last word in a given string.

given number n return matrix n by n with numbers in spiral order

Classic FizzBuzz: return a list from 1 to n with Fizz/Buzz substitutions.

Return true if any value appears at least twice in the array.

Find the contiguous subarray with the largest sum and return that sum.

Return the nth Fibonacci number (0-indexed).

Compute n! (the factorial of a non-negative integer n).

Move all zeroes to the end while keeping the order of non-zero elements.

Every element appears twice except one. Find the single one.

Maximize profit from a single buy/sell of a stock given daily prices.

Determine whether one string is an anagram of another.

Return the index of target in a sorted array, or -1 if not present.

Count the number of vowels in a string.

Count distinct ways to climb n stairs taking 1 or 2 steps at a time.

Return an array where each element is the product of all others.

Given an elevation map, compute how much water it can trap after raining.

Find the minimum number of edit operations to convert one word into another.

Find the median of two sorted arrays in logarithmic time.

Find the length of the longest valid well-formed parentheses substring.

Determine whether an integer reads the same backward as forward.

Add one to a number represented as an array of digits.

Find the element that appears more than half the time in an array.

Check whether one string is a subsequence of another.

Find the index of the first non-repeating character in a string.

Return the index where a target should be inserted into a sorted array.

Maximize the loot from non-adjacent houses along a street.

Decide whether you can reach the last index of an array of jump lengths.

Find the fewest coins needed to make up a given amount.

Find the length of the longest substring without repeating characters.

Find two lines that together with the x-axis hold the most water.

Count the number of islands in a grid of land and water cells.

Determine whether a string can be segmented into words from a dictionary.

Find the length of the longest strictly increasing subsequence.

Find the area of the largest rectangle that fits under a histogram.

Return the maximum of every contiguous window of size k.

Find the minimum number of jumps needed to reach the last index.