Array

Sort an Array in a Waveform

Sort the Matrix Diagonally

Print the Matrix in Spiral Manner

Maximum Product Subarray in an Array

Reverse Pairs

Count Inversions

Find the Repeating and Missing Number

Find the Majority of Element that occurs more than N/3 times

Four Sum Problem

Find the Element that Appears Once in an Array Where Every Other Element Appears Thrice

Find the unique number in an array where every other element appears thrice. Learn efficient C++ approaches using hash maps, bit counting, and sorting with optimal time and space.

Find the Single Number in an Array Where All Others Appear Twice

Find the single non-repeating element in an array where every other element appears twice. Solve it using hashmap or optimal XOR-based bit manipulation in C++ with O(n) time.