Program for Nth Catalan Number Catalan numbers (Cn) are a sequence of natural numbers. Nth Catalan number has applications in many counting problems. Competitive Programming, Dynamic Programming, Mathematics

How to calculate Binomial Coefficient (nCr) in O(r) time complexity The recomputations in calculating binomial coefficient (nCr) can be avoided by exploiting optimal substructure and overlapping subproblems Competitive Programming, Dynamic Programming, Mathematics

Array Manipulation | HackerRank Solution [Hard] Starting with a 1-indexed array of zeros and a list of operations, for each operation add a value to each the array element between two given indices, inclusive. Once all operations have been performed, return the maximum value in the array. Arrays, Competitive Programming, Sorting

Palindrome Index | HackerRank Solution [Easy] Given a string of lowercase letters in the range ascii[a-z], determine the index of a character that can be removed to make the string a palindrome Competitive Programming, Greedy approach

Sherlock and MiniMax | HackerRank Solution [Hard] Given an integer range, for all M in that inclusive range, determine the minimum (abs(arr[i]-M) for all 1 <= i <= size[a] Arrays, Competitive Programming, Mathematics

Sherlock and Array | HackerRank Solution [Easy] Challenge is to find an element of the array such that the sum of all elements to the left is equal to the sum of all elements to the right Arrays

PacMan – DFS | HackerRank Solution [Easy] Print all the nodes that you encounter while printing DFS tree. Then, print the distance ‘D’ between the source ‘P’ and the destination ‘.’ Competitive Programming, Depth First Search (DFS)

Reverse Shuffle Merge | HackerRank Solution [Advanced] Given a string s such that, s ∈ merge(reverse(A), shuffle(A)) for some string A, find the lexicographically smallest A Competitive Programming

map vs unordered_map in C++ Standard Template Library (STL) Internally, the elements in the unordered_map are not sorted in any particular order with respect to either their key or values (unlike map) C/C++, Hashmaps

nCr table | HackerRank Solution [Medium] Jim is doing his discrete maths homework which requires him to repeatedly calculate nCr(n choose r) for different values of n Dynamic Programming, Mathematics