Summary

Two Pointers

• 167. Two Sum
• 88. Merge Sorted Array
• 21. Merge Two Sorted Lists
• 86. Partition List
• 23. Merging k Sorted Lists (heapq)
• 19. The k-th Element from the End of a Linked List
• 876. Middle of the Linked List
• 141. Detect Cycle in a Linked List
• 160. Intersection of Two Linked Lists

Sliding window

• 76. Minimum Window Substring
• 567. Permutation in String

Depth-First Search (DFS)

For queue, mark things as visited when we add them into the queue!!!

• 695. Max Area of Island
• 547. Number of Provinces
• 417. Pacific Atlantic Water Flow

Backtrack

• 46. Permutations
• 77. Combinations
• 79. Word Search
• 51. N-Queens

Breadth-First Search (BFS)

BFS is good for shortest path problems NOTE:

1) Visited nodes need to be marked when entering 2) set is faster than list for "in" operation

• 1091. Shortest Path in Binary Matrix (depth added to queue)
• 934. Shortest Bridge
• 127. Word Ladder

Dynamic Programming (DP)

NOTE:

1) n+1 initialization is really helpful

• 70. Climbing Stairs
• 198. House Robber
• 413. Arithmetic Slices

Greedy Algorithm

• 455. Assign Cookies
• 135. Candy

1.1 Basic Knowledge Data Structure

1.2 Basic Knowledge Sort

2.1 Linked List Linked List

2.2 Array Array

2.3 Binary Tree Binary Tree