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Arrays & Strings
Big O Notation: Time & Space Complexity
Static Arrays, Dynamic Arrays & Strings
Full Python Course for Beginners
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Find Closest Number to Zero | Easy |  |
3/10 | ✖ |
| Merge Strings Alternately | Easy | |
4/10 | ✖ |
| Roman to Integer | Easy | |
4.5/10 | ✖ |
| Is Subsequence | Easy | |
4.5/10 | ✖ |
| Best Time to Buy and Sell Stock | Easy | |
5/10 | ✖ |
| Longest Common Prefix | Easy | |
5/10 | ✖ |
| Summary Ranges | Easy | |
5/10 | ✖ |
| Product of Array Except Self | Medium | |
7/10 | ✖ |
| Merge Intervals | Medium | |
8/10 | ✖ |
| Spiral Matrix | Medium | |
8/10 | ✖ |
| Rotate Image | Medium | |
9/10 | ✖ |
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Arrays & Strings
Big O Notation: Time & Space Complexity
Static Arrays, Dynamic Arrays & Strings
Full Python Course for Beginners
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Find Closest Number to Zero | Easy | |
✖ |
| Merge Strings Alternately | Easy | |
✖ |
| Roman to Integer | Easy | |
✖ |
| Is Subsequence | Easy | |
✖ |
| Best Time to Buy and Sell Stock | Easy | |
✖ |
| Longest Common Prefix | Easy | |
✖ |
| Summary Ranges | Easy | |
✖ |
| Product of Array Except Self | Medium | |
✖ |
| Merge Intervals | Medium | |
✖ |
| Spiral Matrix | Medium | |
✖ |
| Rotate Image | Medium | |
✖ |
Hashmaps & Sets
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Jewels and Stones | Easy | |
3/10 | ✖ |
| Contains Duplicate | Easy | |
3/10 | ✖ |
| Ransom Note | Easy | |
4/10 | ✖ |
| Valid Anagram | Easy | |
5/10 | ✖ |
| Maximum Number of Balloons | Easy | |
6/10 | ✖ |
| Two Sum | Easy | |
6/10 | ✖ |
| Valid Sudoku | Medium | |
6.5/10 | ✖ |
| Group Anagrams | Medium | |
7.5/10 | ✖ |
| Majority Element | Easy | |
8/10 | ✖ |
| Longest Consecutive Sequence | Hard | |
8.5/10 | ✖ |
You must be signed in to mark questions as solved.
Hashmaps & Sets
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Jewels and Stones | Easy | |
✖ |
| Contains Duplicate | Easy | |
✖ |
| Ransom Note | Easy | |
✖ |
| Valid Anagram | Easy | |
✖ |
| Maximum Number of Balloons | Easy | |
✖ |
| Two Sum | Easy | |
✖ |
| Valid Sudoku | Medium | |
✖ |
| Group Anagrams | Medium | |
✖ |
| Majority Element | Easy | |
✖ |
| Longest Consecutive Sequence | Hard | |
✖ |
2 Pointers
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Squares of a Sorted Array | Easy | |
4/10 | ✖ |
| Reverse String | Easy | |
4/10 | ✖ |
| Two Sum II - Input Array Is Sorted | Medium | |
5/10 | ✖ |
| Valid Palindrome | Easy | |
5/10 | ✖ |
| 3Sum | Medium | |
7/10 | ✖ |
| Container With Most Water | Medium | |
7.5/10 | ✖ |
| Trapping Rain Water | Hard | |
9/10 | ✖ |
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2 Pointers
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Squares of a Sorted Array | Easy | |
✖ |
| Reverse String | Easy | |
✖ |
| Two Sum II - Input Array Is Sorted | Medium | |
✖ |
| Valid Palindrome | Easy | |
✖ |
| 3Sum | Medium | |
✖ |
| Container With Most Water | Medium | |
✖ |
| Trapping Rain Water | Hard | |
✖ |
Stacks
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Baseball Game | Easy | |
4/10 | ✖ |
| Valid Parentheses | Easy | |
5.5/10 | ✖ |
| Evaluate Reverse Polish Notation (RPN) | Medium | |
6/10 | ✖ |
| Daily Temperatures | Medium | |
6.5/10 | ✖ |
| Min Stack | Medium | |
7/10 | ✖ |
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Stacks
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Baseball Game | Easy | |
✖ |
| Valid Parentheses | Easy | |
✖ |
| Evaluate Reverse Polish Notation (RPN) | Medium | |
✖ |
| Daily Temperatures | Medium | |
✖ |
| Min Stack | Medium | |
✖ |
Linked Lists
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Remove Duplicates from Sorted List | Easy | |
4/10 | ✖ |
| Reverse Linked List | Easy | |
5/10 | ✖ |
| Merge Two Sorted Lists | Easy | |
5/10 | ✖ |
| Linked List Cycle | Easy | |
6/10 | ✖ |
| Middle of the Linked List | Easy | |
6/10 | ✖ |
| Remove Nth Node from End of List | Medium | |
6/10 | ✖ |
| Copy List with Random Pointer | Medium | |
7/10 | ✖ |
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Linked Lists
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Remove Duplicates from Sorted List | Easy | |
✖ |
| Reverse Linked List | Easy | |
✖ |
| Merge Two Sorted Lists | Easy | |
✖ |
| Linked List Cycle | Easy | |
✖ |
| Middle of the Linked List | Easy | |
✖ |
| Remove Nth Node from End of List | Medium | |
✖ |
| Copy List with Random Pointer | Medium | |
✖ |
Binary Search
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Binary Search | Easy | |
3/10 | ✖ |
| Search Insert Position | Easy | |
3.5/10 | ✖ |
| First Bad Version | Easy | |
4/10 | ✖ |
| Valid Perfect Square | Easy | |
4/10 | ✖ |
| Search a 2D Matrix | Medium | |
5/10 | ✖ |
| Find Minimum in Rotated Sorted Array | Medium | |
6/10 | ✖ |
| Search in Rotated Sorted Array | Medium | |
7/10 | ✖ |
| Koko Eating Bananas | Medium | |
7/10 | ✖ |
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Binary Search
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Binary Search | Easy | |
✖ |
| Search Insert Position | Easy | |
✖ |
| First Bad Version | Easy | |
✖ |
| Valid Perfect Square | Easy | |
✖ |
| Search a 2D Matrix | Medium | |
✖ |
| Find Minimum in Rotated Sorted Array | Medium | |
✖ |
| Search in Rotated Sorted Array | Medium | |
✖ |
| Koko Eating Bananas | Medium | |
✖ |
Sliding Window
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Maximum Average Subarray I | Easy | |
5/10 | ✖ |
| Max Consecutive Ones III | Medium | |
5/10 | ✖ |
| Longest Substring Without Repeating Characters | Medium | |
5.5/10 | ✖ |
| Longest Repeating Character Replacement | Medium | |
6/10 | ✖ |
| Minimum Size Subarray Sum | Medium | |
6/10 | ✖ |
| Permutation in String | Medium | |
7/10 | ✖ |
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Sliding Window
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Maximum Average Subarray I | Easy | |
✖ |
| Max Consecutive Ones III | Medium | |
✖ |
| Longest Substring Without Repeating Characters | Medium | |
✖ |
| Longest Repeating Character Replacement | Medium | |
✖ |
| Minimum Size Subarray Sum | Medium | |
✖ |
| Permutation in String | Medium | |
✖ |
Trees
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Invert Binary Tree | Easy | |
3/10 | ✖ |
| Maximum Depth of Binary Tree | Easy | |
4/10 | ✖ |
| Balanced Binary Tree | Easy | |
5/10 | ✖ |
| Diameter of Binary Tree | Easy | |
5/10 | ✖ |
| Same Binary Tree | Easy | |
5/10 | ✖ |
| Symmetric Tree | Easy | |
5/10 | ✖ |
| Path Sum | Easy | |
5.5/10 | ✖ |
| Subtree of Another Tree | Medium | |
5.5/10 | ✖ |
| Binary Tree Level Order Traversal (BFS) | Medium | |
6/10 | ✖ |
| Kth Smallest Element in a BST | Medium | |
6.5/10 | ✖ |
| Minimum Absolute Difference in BST | Easy | |
6.5/10 | ✖ |
| Validate Binary Search Tree | Medium | |
6.5/10 | ✖ |
| Lowest Common Ancestor of a Binary Search Tree | Medium | |
7/10 | ✖ |
| Implement Trie (Prefix Tree) | Medium | |
8/10 | ✖ |
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Trees
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Invert Binary Tree | Easy | |
✖ |
| Maximum Depth of Binary Tree | Easy | |
✖ |
| Balanced Binary Tree | Easy | |
✖ |
| Diameter of Binary Tree | Easy | |
✖ |
| Same Binary Tree | Easy | |
✖ |
| Symmetric Tree | Easy | |
✖ |
| Path Sum | Easy | |
✖ |
| Subtree of Another Tree | Medium | |
✖ |
| Binary Tree Level Order Traversal (BFS) | Medium | |
✖ |
| Kth Smallest Element in a BST | Medium | |
✖ |
| Minimum Absolute Difference in BST | Easy | |
✖ |
| Validate Binary Search Tree | Medium | |
✖ |
| Lowest Common Ancestor of a Binary Search Tree | Medium | |
✖ |
| Implement Trie (Prefix Tree) | Medium | |
✖ |
Heaps
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Last Stone Weight | Easy | |
5/10 | ✖ |
| Kth Largest Element in an Array | Medium | |
6/10 | ✖ |
| Top K Frequent Elements | Medium | |
6/10 | ✖ |
| K Closest Points to Origin | Medium | |
6.5/10 | ✖ |
| Merge K Sorted Linked Lists | Hard | |
8/10 | ✖ |
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Heaps
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Last Stone Weight | Easy | |
✖ |
| Kth Largest Element in an Array | Medium | |
✖ |
| Top K Frequent Elements | Medium | |
✖ |
| K Closest Points to Origin | Medium | |
✖ |
| Merge K Sorted Linked Lists | Hard | |
✖ |
Recursive Backtracking
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Subsets | Medium | |
6/10 | ✖ |
| Permutations | Medium | |
6/10 | ✖ |
| Combinations | Medium | |
6.5/10 | ✖ |
| Combination Sum | Medium | |
7/10 | ✖ |
| Letter Combinations of a Phone Number | Medium | |
7/10 | ✖ |
| Generate Parentheses | Medium | |
8/10 | ✖ |
| Word Search | Medium | |
9/10 | ✖ |
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Recursive Backtracking
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Subsets | Medium | |
✖ |
| Permutations | Medium | |
✖ |
| Combinations | Medium | |
✖ |
| Combination Sum | Medium | |
✖ |
| Letter Combinations of a Phone Number | Medium | |
✖ |
| Generate Parentheses | Medium | |
✖ |
| Word Search | Medium | |
✖ |
Graphs
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Find if Path Exists in Graph | Easy | |
5/10 | ✖ |
| Number of Islands | Medium | |
7/10 | ✖ |
| Max Area of Island | Medium | |
7/10 | ✖ |
| Course Schedule (Detecting Cycles in a Graph) | Medium | |
7/10 | ✖ |
| Course Schedule II (Topological Sort) | Medium | |
7/10 | ✖ |
| Pacific Atlantic Water Flow | Medium | |
8/10 | ✖ |
| Clone Graph | Medium | |
8/10 | ✖ |
| Rotting Oranges | Medium | |
8/10 | ✖ |
| Min Cost to Connect All Points (Prim's Algorithm to Create MST) | Medium | |
8.5/10 | ✖ |
| Network Delay Time (Dijkstra's Algorithm) | Medium | |
8.5/10 | ✖ |
You must be signed in to mark questions as solved.
Graphs
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Find if Path Exists in Graph | Easy | |
✖ |
| Number of Islands | Medium | |
✖ |
| Max Area of Island | Medium | |
✖ |
| Course Schedule (Detecting Cycles in a Graph) | Medium | |
✖ |
| Course Schedule II (Topological Sort) | Medium | |
✖ |
| Pacific Atlantic Water Flow | Medium | |
✖ |
| Clone Graph | Medium | |
✖ |
| Rotting Oranges | Medium | |
✖ |
| Min Cost to Connect All Points (Prim's Algorithm to Create MST) | Medium | |
✖ |
| Network Delay Time (Dijkstra's Algorithm) | Medium | |
✖ |
Dynamic Programming
| Problem | Difficulty | Leetcode | Difficulty Score | Status |
|---|---|---|---|---|
| Fibonacci Number | Easy | |
5/10 | ✖ |
| Climbing Stairs | Easy | |
5/10 | ✖ |
| Min Cost Climbing Stairs | Easy | |
6/10 | ✖ |
| House Robber | Medium | |
6/10 | ✖ |
| Unique Paths | Medium | |
6/10 | ✖ |
| Maximum Subarray (Kadane's Algorithm) | Medium | |
6.5/10 | ✖ |
| Jump Game | Medium | |
7.5/10 | ✖ |
| Coin Change | Medium | |
7.5/10 | ✖ |
| Longest Increasing Subsequence | Medium | |
8/10 | ✖ |
| Longest Common Subsequence | Medium | |
10/10 | ✖ |
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Dynamic Programming
| Problem | Difficulty | Leetcode | Status |
|---|---|---|---|
| Fibonacci Number | Easy | |
✖ |
| Climbing Stairs | Easy | |
✖ |
| Min Cost Climbing Stairs | Easy | |
✖ |
| House Robber | Medium | |
✖ |
| Unique Paths | Medium | |
✖ |
| Maximum Subarray (Kadane's Algorithm) | Medium | |
✖ |
| Jump Game | Medium | |
✖ |
| Coin Change | Medium | |
✖ |
| Longest Increasing Subsequence | Medium | |
✖ |
| Longest Common Subsequence | Medium | |
✖ |
