| S.no. | Title | Link | SolutionApproachUsed | DataStructuresUsed | Level(Hard/Med/Easy) |
|---|---|---|---|---|---|
| 1 | Two Sum | two-sum.py | Use hashmap for O(n) efficiency | Hash Map | Easy |
| 2 | Best Time to Buy and Sell Stock | best-time-to-buy-and-sell-stock.py | Track min price and max profit | Array | Easy |
| 3 | Valid Palindrome | valid-palindrome.py | Filter alphanumeric and check palindrome | String | Easy |
| 4 | Longest Consecutive Sequence | longest-consecutive-sequence.py | Set to find sequences, then iterate | Set | Hard |
| 5 | Minimum Garden Perimeter to Collect Enough Apples | minimum-garden-perimeter-to-collect-enough-apples.java | Increment perimeter until apples met | Math | Medium |
| 6 | Single Number | single-number.py | Bitwise XOR to isolate single number | Bit Manipulation | Easy |
| 7 | Longest Common Prefix | longest-common-prefix.py | Sort and compare first and last strings | Array | Easy |
| 8 | Two Sum II - Input Array Is Sorted | two-sum-ii-input-array-is-sorted.py | Two pointers from ends to middle | Array | Medium |
| 9 | Letter Combinations of a Phone Number | letter-combinations-of-a-phone-number.java | Recursive combination generation | String, Recursion | Medium |
| 10 | Factorial Trailing Zeroes | factorial-trailing-zeroes.py | Count multiples of 5 in n! | Math | Easy |
| 11 | Remove Nth Node From End of List | remove-nth-node-from-end-of-list.java | Two pointers with n gap | Linked List | Medium |
| 12 | Count Primes | count-primes.java | Sieve of Eratosthenes | Array | Easy |
| 13 | Kth Largest Element in an Array | kth-largest-element-in-an-array.py | Min-heap for top K elements | Heap | Medium |
| 14 | Contains Duplicate | contains-duplicate.py | Hashset to track duplicates | Hash Set | Easy |
| 15 | Palindrome Linked List | palindrome-linked-list.java | Convert to list and check palindrome | Linked List | Easy |
| 16 | Product of Array Except Self | product-of-array-except-self.py | Left and right product lists | Array | Medium |
| 17 | Valid Anagram | valid-anagram.py | Check if t is permutation of s | Hash Map | Easy |
| 18 | Missing Number | missing-number.py | Sort and find missing number | Math | Easy |
| 19 | Encode and Decode Strings | encode-and-decode-strings.py | Length header for each string | String | Medium |
| 20 | Move Zeroes | move-zeroes.py | Two pointers to swap non-zero elements | Array | Easy |
| 21 | Bulb Switcher | bulb-switcher.java | Math.sqrt to find the switch count | Math | Medium |
| 22 | Top K Frequent Elements | top-k-frequent-elements.py | Heap to find top K frequent elements | Heap | Medium |
| 23 | Valid Sudoku | valid-sudoku.py | Sets to check row, column, and box validity | Hash Set | Medium |
| 24 | Sudoku Solver | sudoku-solver.java | Backtracking to solve the puzzle | Backtracking | Hard |
| 25 | Fizz Buzz | fizz-buzz.py | Iterate and check divisibility by 3 and 5 | Array | Easy |
| 26 | Trapping Rain Water | trapping-rain-water.py | Two pointers to calculate trapped water | Array | Hard |
| 27 | Group Anagrams | group-anagrams.py | Categorize by sorted string | Hash Map | Medium |
| 28 | Pow(x, n) | powx-n.py | Direct computation | Math | Medium |
| 29 | N-Queens | n-queens.java | Backtracking to place queens | Backtracking | Hard |
| 30 | Contiguous Array | contiguous-array.py | Hash map to track count balance | Hash Map | Medium |
| 31 | Permutation in String | permutation-in-string.py | Sliding window with character count | Hash Map | Medium |
| 32 | Reverse Integer | reverse-integer.py | Reverse digits of the integer | Math | Easy |
| 33 | Binary Search | binary-search.py | Binary search algorithm | Array | Easy |
| 34 | Palindrome Number | palindrome-number.py | Check if integer is palindrome without converting | Math | Easy |
| 35 | Linked List Cycle | linked-list-cycle.java | Fast and slow pointers to detect cycle | Linked List | Easy |
| 36 | Min Stack | min-stack.java | Design a stack that supports min in O(1) time | Stack | Easy |
| 37 | Valid Parentheses | valid-parentheses.java | Stack to check for balanced parentheses | Stack | Easy |
| 38 | Merge Two Sorted Lists | merge-two-sorted-lists.java | Merge two linked lists iteratively | Linked List | Easy |
| 39 | Merge k Sorted Lists | merge-k-sorted-lists.java | Re-use mergeTwoLists code and DAQ approach | Linked List, Heap | Hard |
| 40 | Assign Cookies | assign-cookies.py | Greedy to satisfy the most children | Array, Greedy | Easy |
| 41 | Permutations | permutations.py | Backtracking | Array, Backtracking | Medium |
| 42 | Image Smoother | image-smoother.py | Iterate and calculate average | Array | Easy |
| 43 | Combination Sum | combination-sum.py | Backtracking to find unique combinations | Array, Backtracking | Medium |
| 44 | Word Search | word-search.py | DFS to search words in a grid | Array, DFS | Medium |
| 45 | Sort the Students by Their Kth Score | sort-the-students-by-their-kth-score.py | Sorting based on criteria | Array | Medium |
| 46 | Subsets | subsets.py | Backtracking to generate all subsets | Array, Backtracking | Medium |
| 47 | Custom Sort String | custom-sort-string.py | Custom sorting logic | String, Hash Map | Medium |
| 48 | Koko Eating Bananas | koko-eating-bananas.py | Binary search to find the minimum speed | Array, Binary Search | Medium |
| 49 | Palindrome Partitioning | palindrome-partitioning.py | Backtracking to find all possible palindrome partitioning | Array, Backtracking | Medium |
| 50 | Evaluate Reverse Polish Notation | evaluate-reverse-polish-notation.py | Evaluate the value of an arithmetic expression in Reverse Polish Notation | Stack | Medium |
| 51 | Generate Parentheses | generate-parentheses.py | Backtracking to generate all combinations of well-formed parentheses | String, Backtracking | Medium |
| 52 | Daily Temperatures | daily-temperatures.py | Stack to find the next greater temperature | Array, Stack | Medium |
| 53 | Car Fleet | car-fleet.py | Sorting and stack to calculate car fleets | Array, Sorting | Medium |
| 54 | Maximum 69 Number | maximum-69-number.py | Greedy to maximize the number | Math | Easy |
| 55 | Number of Employees Who Met the Target | number-of-employees-who-met-the-target.py | Analyzing employee performance data | Array | Medium |
| 56 | Longest Substring Without Repeating Characters | longest-substring-without-repeating-characters.py | Sliding window to find unique substring | String, Hash Map | Medium |
| 57 | Split the Array | split-the-array.py | Divide array into segments | Array, Greedy | Medium |
| 58 | Longest Repeating Character Replacement | longest-repeating-character-replacement.py | Sliding window with character count | String, Hash Map | Medium |
| 59 | Minimum Window Substring | minimum-window-substring.py | Sliding window to cover all characters | String, Hash Map | Hard |
| 60 | Longest Common Subsequence | longest-common-subsequence.py | Dynamic programming to find subsequence | Array, DP | Medium |
| 61 | Climbing Stairs | climbing-stairs.py | Dynamic programming for step combinations | Math, DP | Easy |
| 62 | Word Break | word-break.py | DP to check word segmentation possibilities | String, DP | Medium |
| 63 | Longest Increasing Subsequence | longest-increasing-subsequence.py | DP for increasing subsequences | Array, DP | Medium |
| 64 | Number of 1 Bits | number-of-1-bits.py | Bit manipulation to count set bits | Bit Manipulation | Easy |
| 65 | Largest Rectangle in Histogram | largest-rectangle-in-histogram.py | Stack to find largest rectangle area | Array, Stack | Hard |
| 66 | Sliding Window Maximum | sliding-window-maximum.py | Deque for maximum in sliding window | Array, Deque | Hard |
| 67 | Length of Last Word | length-of-last-word.py | Iteration and String Manipulation | String | Easy |
I am aware that links are broken as of now [FIXED] ✅