堆，栈，队列，哈希表

注意各个数据结构的基本原理，增删查改复杂度。

Queue 题目：

• Leetcode 225。Implement Stack using Queues
• Leetcode 346。Moving Average from Data Stream
• Leetcode 281。Zigzag Iterator
• Leetcode 1429。First Unique Number
• Leetcode 54。Spiral Matrix
• Leetcode 362。Design Hit Counter

Stack 题目：

• Leetcode 155。Min Stack (follow up Leetcode 716 Max Stack)
• Leetcode 232。Implement Queue using Stacks
• Leetcode 150。Evaluate Reverse Polish Notation
• Leetcode 224。Basic Calculator II (I，II，III，IV)
• Leetcode 20。Valid Parentheses
• Leetcode 1472。Design Browser History
• Leetcode 1209。Remove All Adjacent Duplicates in String II
• Leetcode 1249。Minimum Remove to Make Valid Parentheses
• Leetcode 735。Asteroid Collision

Hashmap/ Hashset 题目：

• Leetcode 1。Two Sum
• Leetcode 146。LRU Cache (Python 中可以使用 OrderedDict 来代替)
• Leetcode 128。Longest Consecutive Sequence
• Leetcode 73。Set Matrix Zeroes
• Leetcode 380。Insert Delete GetRandom O(1)
• Leetcode 49。Group Anagrams
• Leetcode 350。Intersection of Two Arrays II
• Leetcode 299。Bulls and Cows
• Leetcode 348 Design Tic-Tac-Toe

Heap／Priority Queue 题目：

• Leetcode 973。K Closest Points
• Leetcode 347。Top k Largest Elements
• Leetcode 23。Merge K Sorted Lists
• Leetcode 264。Ugly Number II
• Leetcode 1086。High Five
• Leetcode 88。Merge Sorted Arrays
• Leetcode 692。Top K Frequent Words
• Leetcode 378。Kth Smallest Element in a Sorted Matrix
• Leetcode 295。Find Median from Data Stream (标准解法是双 heap，但是 SortedDict 会非常容易)
• Leetcode 767。Reorganize String
• Leetcode 1438。Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit (这个题用单调双端队列、TreeMap、双 heap 都可以)
• Leetcode 895。Maximum Frequency Stack