8 Data Structure

Major:
Hash Function
Top k Largest Numbers (Ladder)
Merge k Sorted Arrays (Ladder)
Rehashing
Merge k Sorted Lists
Implement Queue by Two Stacks
Min Stack
Ugly Number II
LRU Cache
Largest Rectangle in Histogram
Minor:
Implement Stack (Ladder)
Implement Stack by Two Queues (Ladder)
Implement Queue by Linked List II (Ladder)
Implement Queue by Linked List (Ladder)
Top k Largest Numbers II (Ladder)
Stack Sorting (Ladder)
Top k Frequent Words (Ladder)
Heapify
Longest Consecutive Sequence
Animal Shelter (Ladder)
LFU Cache (Ladder)
Max Tree (Ladder)