# Coding interview problems

### Two Sum

Free. No login required. Python technical interview question: Two Sum

### Merge Intervals

Given a collection of intervals, merge any overlapping intervals.

### Reverse a String

reverse a string interview question

### Longest Common Prefix

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

### Palindrome String

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

### Roman to Integer

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

### Letter Combinations of a Phone Number

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

valid parentheses coding question

### Find the Index of the First Occurrence in a String

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

### Length of Last Word

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

### Spiral Matrix

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