# Status Problem video Level Completes Likes 430 Longest substring with at most K unique characters Medium % 2 388 Sort a given stack - Using Temporary Stack Medium % 0 367 Sum of all Unique elements in a given array Beginner % 0 349 Selection Sort Beginner % 0 338 Find Number of reverse pairs in an array Hard % 1 332 Insertion Sort Beginner % 0 328 Heap Sort Medium % 0 321 Bubble Sort and Optimized Bubble Sort Beginner % 1 150 Sort Names by their Last Names. Beginner % 0 143 Merge K Sorted Arrays Hard % 0 114 Counting Sort Medium % 0 110 Sort 3 Integers without using if condition OR use only Max() function. Beginner % 0 102 Merge Sort in a Linked list Medium % 0 57 Sort an Array According to the Order Defined by Another Array Medium % 0 56 Sort an Array - odd numbers appear first in ascending order followed by the even numbers in descending order. Medium % 0 12 Efficient Methods to Find Pairs with Sum K in an Array Beginner % 0 10 Quick Sort Implementation Medium % 0 2 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 Find Number of reverse pairs in an array Insertion Sort Heap Sort Bubble Sort and Optimized Bubble Sort 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 Array According to the Order Defined by Another Array Sort an Array - odd numbers appear first in ascending order followed by the even numbers in descending order. Efficient Methods to Find Pairs with Sum K in an Array Quick Sort Implementation Merge Sort - Updated - Most Efficient ways to Implement 1