Problems pattern frequency

Dynamic Programming : 13DFS : 11BFS : 9Backtracking : 8Arrays : 6Graph : 6Heap : 6Binary Search : 4Two Pointers : 4Intervals : 4Topological Sort : 4Fast & Slow Pointers : 3Union Find : 2Greedy : 2Sliding Window : 2Trie : 2In-place reversal of a linked list : 1QuickSelect : 1Design : 1

Leetcode Patterns
Total: 0/171 Easy: 0/36 Medium: 0/105 Hard: 0/30	Questions	Solutions	Show/Hide Patterns	Difficulty	Companies
	Product of Array Except Self		Arrays	Medium
	Find the Duplicate Number		ArraysBinary SearchTwo Pointers	Medium
	Find All Duplicates in an Array		Arrays	Medium
	Spiral Matrix		Arrays	Medium
	Rotate Image		Arrays	Medium
	Word Search		Backtracking	Medium
	Longest Consecutive Sequence		Arrays	Medium
	Subsets		Backtracking	Medium
	Permutations		Backtracking	Medium
	Combinations		Backtracking	Medium
	Combination Sum III		Backtracking	Medium
	Generate Parentheses		Backtracking	Medium
	Letter Combinations of a Phone Number		Backtracking	Medium
	Generalized Abbreviation		Backtracking	Medium
	House Robber		Dynamic Programming	Medium
	House Robber II		Dynamic Programming	Medium
	Coin Change		Dynamic Programming	Medium
	Maximum Product Subarray		Dynamic Programming	Medium
	Longest Increasing Subsequence		Dynamic Programming	Medium
	Longest Palindromic Substring		Dynamic Programming	Medium
	Word Break		Dynamic Programming	Medium
	Combination Sum IV		Dynamic Programming	Medium
	Decode Ways		Dynamic Programming	Medium
	Unique Paths		Dynamic Programming	Medium
	Palindromic Substrings		Dynamic Programming	Medium
	Number of Longest Increasing Subsequence		Dynamic Programming	Medium
	Partition Equal Subset Sum		Dynamic Programming	Medium
	Add Two Numbers		Fast & Slow Pointers	Medium
	Remove Nth Node From End Of List		Fast & Slow Pointers	Medium
	Reorder List		Fast & Slow Pointers	Medium
	Clone Graph		BFSDFSGraph	Medium
	Pacific Atlantic Water Flow		BFSDFS	Medium
	Number of Islands		BFSDFSUnion Find	Medium
	Graph Valid Tree		BFSDFSGraphUnion Find	Medium
	Reverse Linked List II		In-place reversal of a linked list	Medium
	Merge Intervals		Intervals	Medium
	Interval List Intersections		Intervals	Medium
	Meeting Rooms II		HeapIntervals	Medium
	Task Scheduler		GreedyHeap	Medium
	Insert Interval		Intervals	Medium
	Find Peak Element		Binary Search	Medium
	Search a 2D Matrix		Binary Search	Medium
	Find K Closest Elements		Binary Search	Medium
	Minimum Size Subarray Sum		Sliding Window	Medium
	Longest Substring Without Repeating Characters		Sliding Window	Medium
	K Closest Points to Origin		Heap	Medium
	Top K Frequent Elements		Heap	Medium
	Kth Largest Element in an Array		HeapQuickSelect	Medium
	Reorganize String		GreedyHeap	Medium
	Course Schedule		BFSDFSGraphTopological Sort	Medium
	Course Schedule II		BFSDFSGraphTopological Sort	Medium
	Minimum Height Trees		BFSGraphTopological Sort	Medium
	Sequence Reconstruction		GraphTopological Sort	Medium
	Binary Tree Level Order Traversal		BFS	Medium
	Binary Tree Zigzag Level Order Traversal		BFS	Medium
	Path Sum II		DFS	Medium
	Path Sum III		DFS	Medium
	Lowest Common Ancestor of a Binary Tree		DFS	Medium
	Maximum Width of Binary Tree		DFS	Medium
	Validate Binary Search Tree		DFS	Medium
	Implement Trie (Prefix Tree)		DesignTrie	Medium
	3 Sum		Two Pointers	Medium
	3 Sum Closest		Two Pointers	Medium
	Container With Most Water		Two Pointers	Medium
	Longest Word in Dictionary		Trie	Medium

If input array is sorted then
- Binary search
- Two pointers

If asked for all permutations/subsets then
- Backtracking

If given a tree then
- DFS
- BFS

If given a graph then
- DFS
- BFS

If given a linked list then
- Two pointers

If recursion is banned then
- Stack

If must solve in-place then
- Swap corresponding values
- Store one or more different values in the same pointer

If asked for maximum/minimum subarray/subset/options then
- Dynamic programming

If asked for top/least K items then
- Heap

If asked for common strings then
- Map
- Trie

Else
- Map/Set for O(1) time & O(n) space
- Sort input for O(nlogn) time and O(1) space

The following sources were used in aggregating this question list:

Blind Curated 75 Question List

https://www.teamblind.com/post/New-Year-Gift---Curated-List-of-Top-100-LeetCode-Questions-to-Save-Your-Time-OaM1orEU

Grokking the Coding Interview

https://www.educative.io/courses/grokking-the-coding-interview

14 Patterns to Ace Any Coding Interview Question

https://hackernoon.com/14-patterns-to-ace-any-coding-interview-question-c5bb3357f6ed