Sort

quick sort (wiki)

• 86. Partition List (partition)
• 75. Sort Colors (three-way partition, repeated elements)
• 215. Kth Largest Element in an Array (two-way partition, binary search, heap) template of quick select
• 347. Top K Frequent Elements
• 973. K Closest Points to Origin

merge sort

• 21. Merge Two Sorted Lists (merge)
• 148. Sort List
• Inversion count (can also be solved with BIT and BST)
  • 315. Count of Smaller Numbers After Self
  • 493. Reverse Pairs
  • 327. Count of Range Sum

heap sort

• 23. Merge k Sorted Lists (merge 2 lists/ heap)
• 378. Kth Smallest Element in a Sorted Matrix (comparator)
• 373. Find K Pairs with Smallest Sums
• 347. Top K Frequent Elements
• 295. Find Median from Data Stream
• 1882. Process Tasks Using Servers
• 1801. Number of Orders in the Backlog
• 1405. Longest Happy String
• 215. Kth Largest Element in an Array

bucket sort (bucket for int and trie for string)

• 49. Group Anagrams
• 274. H-Index
• 164. Maximum Gap
• 296. Best Meeting Point
• 347. Top K Frequent Elements (heap / bucket)
• 451. Sort Characters By Frequency

insertion sort

• 147. Insertion Sort List

wiggle sort

• 280. Wiggle Sort
• 324. Wiggle Sort II (find kth, three-way partition)

customize comparator

• 179. Largest Number
• 791. Custom Sort String
• 692. Top K Frequent Words

interval

• 252. Meeting Rooms (greedy)
• 253. Meeting Rooms II (greedy, heap)
• 56. Merge Intervals
• 57. Insert Interval

intersection

• 349. Intersection of Two Arrays
• 350. Intersection of Two Arrays II

Misc

• 945. Minimum Increment to Make Array Unique