Welcome

This page contains solutions to common interview problems that may be encountered.

Arrays

• Longest Substring Without Repeating Characters
• Rotate a 2D Matrix
• Buy/Sell Two Stocks
• Merge Intervals
• Next Permutation
• Random Permutation
• Replace all occurrences of a space with a string

Linked Lists

• Reversing sublists of singly linked lists
• Cycles in singly linked lists
• Overlapping singly linked lists
• Merging two sorted singly linked lists
• Merge k sorted lists

Recursion

• Counting the path of sums
• Money Denominations
• Phone Number Mnemonics
• Unique Permutation

Dynamic Programming

• Perfect Squares
• Find the Maximum Min Path

Binary Trees

• Tree Symmetry
• Iterative In-Order Traversal of a Binary Tree
• Construct a Binary Tree from Pre-Order Traversal and In-Order Traversal

BST

• Validate a BST

Binary Heaps

• Merge k sorted lists

Graphs

• Find a path in a maze from start to finish
• Flip colors in a matrix

Search

• Search in a rotated sorted array
• Find the Duplicate Number

Greedy Algorithms

• Queue Reconstruction By Height

Trie

• Build a Trie in Python

Invariant

• Compute the max. water trapped by a pair of vertical lines