# Status Problem Level Completes Likes 1 Longest substring with at most K unique characters Medium % 2 2 Sort a given stack - Using Temporary Stack Medium % 0 3 Sum of all Unique elements in a given array Beginner % 0 4 Selection Sort – Java Implementation Beginner % 0 5 Find Number of reverse pairs in an array Hard % 1 6 Insertion Sort – Java Implementation Beginner % 0 7 Heap Sort – Java Implementation Medium % 0 8 Bubble Sort and Optimized Bubble Sort- Java Implementation Beginner % 1 9 Sort Names by their Last Names. Beginner % 0 10 Merge K Sorted Arrays Hard % 0 11 Counting Sort Medium % 0 12 Sort 3 Integers without using if condition OR use only Max() function. Beginner % 0 13 Merge Sort in a Linked list Medium % 0 14 Sort an Given Array in the order defined by another array Medium % 0 15 Sort an Array - odd numbers appear first in ascending order followed by the even numbers in descending order. Medium % 0 16 Find a pair of numbers from an array whose sum equals k Beginner % 0 17 Quick Sort Implementation Medium % 0 18 Merge Sort - Updated - Most Efficient ways to Implement Medium % 1 Longest substring with at most K unique characters Sort a given stack - Using Temporary Stack Sum of all Unique elements in a given array Selection Sort – Java Implementation Find Number of reverse pairs in an array Insertion Sort – Java Implementation Heap Sort – Java Implementation Bubble Sort and Optimized Bubble Sort- Java Implementation Sort Names by their Last Names. Merge K Sorted Arrays Counting Sort Sort 3 Integers without using if condition OR use only Max() function. Merge Sort in a Linked list Sort an Given Array in the order defined by another array Sort an Array - odd numbers appear first in ascending order followed by the even numbers in descending order. Find a pair of numbers from an array whose sum equals k Quick Sort Implementation Merge Sort - Updated - Most Efficient ways to Implement 1