| Arrays: Left Rotation |
Given an array and a number, d, perform d left rotations on the array. |
Python |
Easy |
| Strings: Making Anagrams |
How many characters should one delete to make two given strings anagrams of each other? |
Python |
Easy |
| Hash Tables: Ransom Note |
Given two sets of dictionaries, tell if one of them is a subset of the other. |
C++ |
Easy |
| Linked Lists: Detect a Cycle |
Given a pointer to the head of a linked list, determine whether the list has a cycle. |
C++ |
Easy |
| Stacks: Balanced Brackets |
Given a string containing three types of brackets, determine if it is balanced. |
C++ |
Medium |
| Queues: A Tale of Two Stacks |
Create a queue data structure using two stacks. |
C++ |
Medium |
| Trees: Is This a Binary Search Tree? |
Given the root of a binary tree, determine if it’s a binary search tree. |
Python |
Medium |
| Heaps: Find the Running Median |
Find the median of the elements after inputting each element. |
C++ |
Hard |
| Tries: Contacts |
Create a Contacts application with the two basic operations: add and find. |
Python |
Hard |
| Sorting: Bubble Sort |
Find the minimum number of conditional checks taking place in Bubble Sort |
Python |
Easy |
| Sorting: Comparator |
Write a Comparator for sorting elements in an array. |
C++ |
Medium |
| Merge Sort: Counting Inversions |
How many shifts will it take to Merge Sort an array? |
Python |
Hard |
| Hash Tables: Ice Cream Parlor |
Help Sunny and Johnny spend all their money during each trip to the Ice Cream Parlor. |
Python |
Medium |
| DFS: Connected Cell in a Grid |
Find the largest connected region in a 2D Matrix. |
C++ |
Hard |
| BFS: Shortest Reach in a Graph |
Implement a Breadth First Search (BFS). |
C++ |
Hard |
| Time Complexity: Primality |
Determine whether or not a number is prime in optimal time. |
C++ |
Medium |
| Recursion: Fibonacci Numbers |
Compute the $n^{th}$ Fibonacci number. |
C++ |
Easy |
| Recursion: Davis’ Staircase |
Find the number of ways to get from the bottom of a staircase to the top if you can jump 1, 2, or 3 stairs at a time. |
C++ |
Medium |
| DP: Coin Change |
Given $m$ distinct dollar coins in infinite quantities, how many ways can you make change for $n$ dollars? |
C++ |
Hard |
| Bit Manipulation: Lonely Integer |
Find the unique element in an array of integer pairs. |
C++ |
Easy |