Beginner Roadmap

DSA Roadmap 2026 — Coding Interview Learning Path

From fundamentals to advanced patterns. Work through each phase in order for the best results.

1

Hash Map / Set

Trade space for time using O(1) lookup to find pairs, duplicates, and frequencies.

6 Easy 6 Medium

	Problem	Difficulty	Frequency
	Contains Duplicate	Easy	High
	Isomorphic Strings	Easy	Medium
	Number of Good Pairs	Easy	Medium
	Two Sum	Easy	High
	Valid Anagram	Easy	High
	Word Pattern	Easy	Medium
	4Sum II	Medium	Medium
	Group Anagrams	Medium	High
	Longest Consecutive Sequence	Medium	High
	LRU Cache	Medium	High
	Subarray Sum Divisible by K	Medium	Medium
	Top K Frequent Elements	Medium	High

2

Two Pointers

Use two indices moving toward each other or in the same direction to solve linear problems.

5 Easy 7 Medium 1 Hard

	Problem	Difficulty	Frequency
	Move Zeroes	Easy	Medium
	Remove Duplicates from Sorted Array	Easy	High
	Squares of a Sorted Array	Easy	High
	Valid Palindrome	Easy	High
	Valid Palindrome II	Easy	High
	3Sum	Medium	High
	4Sum	Medium	Medium
	Boats to Save People	Medium	Medium
	Container With Most Water	Medium	High
	Minimum Length of String After Deleting Similar Ends	Medium	Low
	Sort Colors	Medium	High
	Two Sum II - Input Array Is Sorted	Medium	High
	Trapping Rain Water	Hard	High

3

Sliding Window

Efficiently process subarrays or substrings of a fixed or variable size.

13 Medium 2 Hard

	Problem	Difficulty	Frequency
	Count Number of Nice Subarrays	Medium	Medium
	Find All Anagrams in a String	Medium	Medium
	Frequency of the Most Frequent Element	Medium	Medium
	Fruit Into Baskets	Medium	Low
	Longest Repeating Character Replacement	Medium	Medium
	Longest Subarray of 1's After Deleting One Element	Medium	Medium
	Longest Substring Without Repeating Characters	Medium	High
	Max Consecutive Ones III	Medium	Medium
	Maximum Number of Vowels in a Substring of Given Length	Medium	Medium
	Minimum Operations to Reduce X to Zero	Medium	Medium
	Minimum Size Subarray Sum	Medium	Medium
	Permutation in String	Medium	Medium
	Subarray Product Less Than K	Medium	Low
	Minimum Window Substring	Hard	High
	Sliding Window Maximum	Hard	Medium

4

Stack

LIFO structure for matching brackets, evaluating expressions, and monotonic problems.

1 Easy 9 Medium

	Problem	Difficulty	Frequency
	Valid Parentheses	Easy	High
	Asteroid Collision	Medium	Medium
	Basic Calculator II	Medium	High
	Car Fleet	Medium	Medium
	Daily Temperatures	Medium	High
	Decode String	Medium	Medium
	Evaluate Reverse Polish Notation	Medium	Medium
	Min Stack	Medium	High
	Remove K Digits	Medium	Medium
	Simplify Path	Medium	Medium

5

Binary Search

Halve the search space each step to find an element or boundary in O(log n).

1 Easy 7 Medium 2 Hard

	Problem	Difficulty	Frequency
	Binary Search	Easy	High
	Capacity to Ship Packages Within D Days	Medium	High
	Find Minimum in Rotated Sorted Array	Medium	High
	Find Peak Element	Medium	Medium
	Koko Eating Bananas	Medium	Medium
	Search a 2D Matrix	Medium	High
	Search in Rotated Sorted Array	Medium	High
	Time Based Key-Value Store	Medium	Medium
	Median of Two Sorted Arrays	Hard	High
	Split Array Largest Sum	Hard	Medium

6

Prefix Sum

Precompute cumulative sums to answer range queries in O(1).

3 Easy 4 Medium

	Problem	Difficulty	Frequency
	Find Pivot Index	Easy	High
	Range Sum Query - Immutable	Easy	Medium
	Running Sum of 1D Array	Easy	Medium
	Contiguous Array	Medium	Medium
	Minimum Average Difference	Medium	Low
	Product of Array Except Self	Medium	High
	Subarray Sum Equals K	Medium	High

7

Linked List

Pointer manipulation for in-place list operations without extra memory.

4 Easy 6 Medium 1 Hard

	Problem	Difficulty	Frequency
	Linked List Cycle	Easy	High
	Merge Two Sorted Lists	Easy	High
	Palindrome Linked List	Easy	High
	Reverse Linked List	Easy	High
	Add Two Numbers	Medium	High
	Copy List with Random Pointer	Medium	High
	Remove Nth Node From End of List	Medium	High
	Reorder List	Medium	Medium
	Rotate List	Medium	Medium
	Swap Nodes in Pairs	Medium	Medium
	Reverse Nodes in k-Group	Hard	High

8

Trees / DFS

Recursive and iterative depth-first traversal for tree structure problems.

4 Easy 10 Medium 2 Hard

	Problem	Difficulty	Frequency
	Diameter of Binary Tree	Easy	High
	Invert Binary Tree	Easy	High
	Maximum Depth of Binary Tree	Easy	High
	Symmetric Tree	Easy	High
	Binary Tree Right Side View	Medium	High
	Construct Binary Tree from Preorder and Inorder Traversal	Medium	Medium
	Count Good Nodes in Binary Tree	Medium	Medium
	Flatten Binary Tree to Linked List	Medium	Medium
	Kth Smallest Element in a BST	Medium	High
	Lowest Common Ancestor of a BST	Medium	High
	Path Sum II	Medium	Medium
	Populating Next Right Pointers in Each Node	Medium	Medium
	Sum Root to Leaf Numbers	Medium	Medium
	Validate Binary Search Tree	Medium	High
	Binary Tree Maximum Path Sum	Hard	High
	Serialize and Deserialize Binary Tree	Hard	Medium

9

Queue / BFS

Level-by-level traversal for shortest paths and layer-based problems.

9 Medium 1 Hard

	Problem	Difficulty	Frequency
	01 Matrix	Medium	High
	Binary Tree Level Order Traversal	Medium	High
	Jump Game III	Medium	Medium
	Minimum Genetic Mutation	Medium	Medium
	Number of Islands	Medium	High
	Open the Lock	Medium	Medium
	Rotting Oranges	Medium	High
	Shortest Path in Binary Matrix	Medium	Medium
	Walls and Gates Premium	Medium	Medium
	Word Ladder	Hard	Medium

10

Heap / Priority Queue

Efficiently track the k-th largest/smallest element or merge sorted sequences.

7 Medium 2 Hard

	Problem	Difficulty	Frequency
	Find K Pairs with Smallest Sums	Medium	Medium
	K Closest Points to Origin	Medium	High
	Kth Largest Element in an Array	Medium	High
	Minimum Cost to Connect Sticks Premium	Medium	Medium
	Reorganize String	Medium	Medium
	Task Scheduler	Medium	Medium
	Top K Frequent Words	Medium	Medium
	Find Median from Data Stream	Hard	High
	Merge K Sorted Lists	Hard	High

11

Backtracking

Explore all possibilities recursively, pruning invalid branches early.

9 Medium 1 Hard

	Problem	Difficulty	Frequency
	Combination Sum	Medium	High
	Combination Sum II	Medium	Medium
	Generate Parentheses	Medium	High
	Letter Combinations of a Phone Number	Medium	High
	Palindrome Partitioning	Medium	Medium
	Permutations	Medium	High
	Subsets	Medium	High
	Subsets II	Medium	Medium
	Word Search	Medium	High
	N-Queens	Hard	Medium

12

Graphs

DFS and BFS on adjacency lists for connectivity, cycles, and path problems.

9 Medium

	Problem	Difficulty	Frequency
	All Paths From Source to Target	Medium	Medium
	Cheapest Flights Within K Stops	Medium	High
	Clone Graph	Medium	High
	Find Eventual Safe States	Medium	Medium
	Minimum Height Trees	Medium	Medium
	Network Delay Time	Medium	Medium
	Number of Connected Components in Undirected Graph Premium	Medium	Medium
	Pacific Atlantic Water Flow	Medium	Medium
	Surrounded Regions	Medium	Medium

13

Dynamic Programming

Break problems into overlapping subproblems and build up solutions bottom-up.

3 Easy 21 Medium 2 Hard

	Problem	Difficulty	Frequency
	Best Time to Buy and Sell Stock	Easy	High
	Climbing Stairs	Easy	High
	Min Cost Climbing Stairs	Easy	High
	Best Time to Buy and Sell Stock with Cooldown	Medium	Medium
	Best Time to Buy and Sell Stock with Transaction Fee	Medium	Medium
	Coin Change	Medium	High
	Decode Ways	Medium	High
	House Robber	Medium	High
	House Robber II	Medium	High
	Integer Break	Medium	Low
	Interleaving String	Medium	Medium
	Longest Common Subsequence	Medium	High
	Longest Increasing Subsequence	Medium	High
	Longest Palindromic Substring	Medium	High
	Maximum Product Subarray	Medium	High
	Maximum Subarray	Medium	High
	Minimum Path Sum	Medium	High
	Palindromic Substrings	Medium	High
	Partition Equal Subset Sum	Medium	High
	Perfect Squares	Medium	Medium
	Target Sum	Medium	High
	Triangle	Medium	Medium
	Unique Paths	Medium	High
	Word Break	Medium	High
	Edit Distance	Hard	Medium
	Regular Expression Matching	Hard	Medium

14

Greedy

Make the locally optimal choice at each step to achieve a globally optimal solution.

7 Medium 1 Hard

	Problem	Difficulty	Frequency
	Gas Station	Medium	Medium
	Jump Game	Medium	High
	Jump Game II	Medium	High
	Meeting Rooms II Premium	Medium	High
	Minimum Number of Arrows to Burst Balloons	Medium	Medium
	Non-overlapping Intervals	Medium	High
	Queue Reconstruction by Height	Medium	Medium
	Candy	Hard	Medium

15

Intervals

Merge, insert, and count overlapping intervals after sorting by start time.

1 Easy 2 Medium 1 Hard

	Problem	Difficulty	Frequency
	Meeting Rooms Premium	Easy	High
	Insert Interval	Medium	High
	Merge Intervals	Medium	High
	Minimum Interval to Include Each Query	Hard	Low

16

Matrix

Navigate 2D grids with DFS/BFS, rotation, spiral traversal, and flood fill.

1 Easy 6 Medium

	Problem	Difficulty	Frequency
	Count Negative Numbers in a Sorted Matrix	Easy	Medium
	Game of Life	Medium	Medium
	Maximal Square	Medium	High
	Rotate Image	Medium	High
	Search a 2D Matrix II	Medium	High
	Set Matrix Zeroes	Medium	High
	Spiral Matrix	Medium	High

17

Bit Manipulation

Use bitwise operations to solve XOR, subset, and number theory problems.

6 Easy 2 Medium

	Problem	Difficulty	Frequency
	Counting Bits	Easy	High
	Missing Number	Easy	High
	Number of 1 Bits	Easy	High
	Power of Two	Easy	Medium
	Reverse Bits	Easy	Medium
	Single Number	Easy	High
	Single Number II	Medium	Medium
	Sum of Two Integers	Medium	Medium

18

Topological Sort

Linear ordering of vertices in a DAG — essential for dependency problems.

4 Medium

	Problem	Difficulty	Frequency
	Course Schedule	Medium	High
	Course Schedule II	Medium	High
	Parallel Courses Premium	Medium	Medium
	Sequence Reconstruction Premium	Medium	Low

19

Union Find

Disjoint set union for grouping, connectivity, and cycle detection.

5 Medium 1 Hard

	Problem	Difficulty	Frequency
	Accounts Merge	Medium	Medium
	Most Stones Removed with Same Row or Column	Medium	Medium
	Number of Provinces	Medium	High
	Redundant Connection	Medium	Medium
	Satisfiability of Equality Equations	Medium	Medium
	Swim in Rising Water	Hard	Medium

20

Trie

Prefix tree for efficient string search, autocomplete, and word matching.

4 Medium 1 Hard

	Problem	Difficulty	Frequency
	Design Add and Search Words Data Structure	Medium	Medium
	Implement Trie (Prefix Tree)	Medium	High
	Longest Word in Dictionary	Medium	Low
	Replace Words	Medium	Medium
	Word Search II	Hard	Medium

21

Monotonic Stack

Maintain a sorted stack to find next/previous greater or smaller elements in O(n).

1 Easy 4 Medium 1 Hard

	Problem	Difficulty	Frequency
	Next Greater Element I	Easy	Medium
	132 Pattern	Medium	Medium
	Online Stock Span	Medium	Medium
	Remove Duplicate Letters	Medium	Medium
	Sum of Subarray Minimums	Medium	Medium
	Largest Rectangle in Histogram	Hard	High