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| # | Problemtext | Tagtag | Leetcodelink | Notesrichtext | Difficultyselect | Tiptext | Prioritypriority |
|---|---|---|---|---|---|---|---|
| 1 | Linked List | Linked ListPattern Template | |||||
| 2 | Graph | GraphPattern Template | |||||
| 3 | Trees & BST | Trees & BSTPattern Template | DFS · BFS · BST Property · Construction | ||||
| 4 | Decision Tree | Meta Skills | |||||
| 5 | How Patterns Build on Each Other | Meta Skills | |||||
| 6 | Production Use-case | Meta Skills | |||||
| 7 | Production Cheat Sheet | Meta Skills | |||||
| 8 | Two Pointer | Two PointerPattern Template | Sorted array, find pair/triplet, converge from both ends, palindrome | ||||
| 9 | Remove Duplicates from Sorted Array | Two Pointer100 DSA | leetcode.com/problems/remove-duplicates-from-sorted-array | Easy | Keep swapping non-equal numbers | ||
| 10 | Move Zeroes to End | Two Pointer100 DSA | leetcode.com/problems/move-zeroes | Easy | Keep swapping non-zero numbers | ||
| 11 | Is Subsequence | Two Pointer | Notes | Easy | Simple loop and check | ||
| 12 | Valid Palindrome | Two Pointer100 DSA | leetcode.com/problems/valid-palindrome | Easy | Regex for isAlphaNum, rest is 2 pointer | ||
| 13 | Next Permutation | Two Pointer | Notes | Medium | Find rightmost ascending pair, swap with next larger, reverse suffix | ||
| 14 | Sort Colors | Two Pointer100 DSA | leetcode.com/problems/sort-colors | Medium | 3 pointer with boundaries (Dutch National Flag) | ||
| 15 | 3Sum | Two Pointer100 DSA | leetcode.com/problems/3sum | Medium | sort, 1 for loop + 1 while loop + 2 pointer | ||
| 16 | 4Sum | Two Pointer | Notes | Medium | 2 loops + 2 pointer | ||
| 17 | 3Sum Closest | Two Pointer | Notes | Medium | Similar to 3 Sum | ||
| 18 | Container With Most Water | Two PointerSliding Window100 DSA | leetcode.com/problems/container-with-most-water | Medium | width x height, just keep finding max by sliding | ||
| 19 | Trapping Rain Water | Two Pointer100 DSA | leetcode.com/problems/trapping-rain-water | Hard | Lmax[] & Rmax[] for every value, then total rmax - height | ||
| 20 | Sliding Window | Sliding WindowPattern Template | Easy | Contiguous subarray/substring, "at most K distinct", window condition | |||
| 21 | Longest Substring Without Repeating Chars | Sliding Window100 DSA | leetcode.com/problems/longest-substring-without-repeating-characters/description | Medium | Map for frequency of characters | ||
| 22 | Minimum Size Subarray Sum | Sliding Window100 DSA | leetcode.com/problems/minimum-size-subarray-sum | Medium | Sliding window is O(n) | ||
| 23 | Minimum Window Substring | Sliding Window100 DSA | leetcode.com/problems/minimum-window-substring | Hard | Expand right to include all chars, shrink left to minimize | ||
| 24 | Max Consecutive 1s | Sliding Window100 DSA | leetcode.com/problems/max-consecutive-ones | Easy | Simple currentCounter & resultCounter | ||
| 25 | Longest Repeating Character Replacement | Sliding Window100 DSA | leetcode.com/problems/longest-repeating-character-replacement/description | Medium | Letters to Replace = (Size of the Window) - (Count of the Most Frequent Character) | ||
| 26 | Fruit Into Baskets | Sliding Window100 DSA | leetcode.com/problems/fruit-into-baskets | Medium | maintain map to check the size, size represents the #of baskets | ||
| 27 | Sliding Window Maximum | Sliding Window100 DSA | leetcode.com/problems/sliding-window-maximum | Hard | simple sliding window and deque | ||
| 28 | Number of Substrings Containing All Three Characters | Sliding Window100 DSA | leetcode.com/problems/number-of-substrings-containing-all-three-characters | Medium | freq array, counting in a sliding window | ||
| 29 | Substrings of Size 3 with Distinct Chars | Sliding Window | Notes | Easy | SW + map | ||
| 30 | Shortest Subarray with Sum ≥ K | Sliding Window | Notes | Hard | Monotonic deque of prefix sums | ||
| 31 | Prefix Sum + HashMap | Prefix + HashMapPattern Template | "Subarray sum = K", "divisible by K", "count subarrays with XOR", set lookup | ||||
| 32 | Subarray Sum Equals K | Prefix + HashMap100 DSA | leetcode.com/problems/subarray-sum-equals-k | Medium | prefixSum - target in map | ||
| 33 | Longest Consecutive Sequence | Prefix + HashMap100 DSA | leetcode.com/problems/longest-consecutive-sequence | Medium | Find smallest, count increments | ||
| 34 | Group Anagrams | Prefix + HashMap100 DSA | leetcode.com/problems/group-anagrams | Medium | Array.from(map.values()) | ||
| 35 | Continuous Subarray Sum | Prefix + HashMap100 DSA | leetcode.com/problems/continuous-subarray-sum | Medium | prefixSum % k seen before → multiple of k | ||
| 36 | Largest Subarray with 0 Sum | Prefix + HashMap100 DSA | www.geeksforgeeks.org/problems/largest-subarray-with-0-sum/1 | Medium | If sum repeats → zero subarray | ||
| 37 | Two Sum | Prefix + HashMap100 DSA | leetcode.com/problems/two-sum | Easy | find target - sum | ||
| 38 | Equilibrium Index | Prefix + HashMap | Notes | Easy | Prefix Sum | ||
| 39 | Intersection of Two Arrays | Prefix + HashMap | Notes | Easy | Insert A1 in set, check A2 | ||
| 40 | Unique Number of Occurrences | Prefix + HashMap | Notes | Easy | Unique occurrences, not unique numbers | ||
| 41 | Partition Array Into Three Parts | Prefix + HashMap | Notes | Medium | Count all sums = sum/3 | ||
| 42 | Binary Search | Binary SearchPattern Template | Sorted input, "minimum maximum", "maximize minimum", "find K-th" | ||||
| 43 | Search in Rotated Sorted Array | Binary Search100 DSA | leetcode.com/problems/search-in-rotated-sorted-array | Medium | If low < mid then left half is sorted | ||
| 44 | Find Peak Element | Binary Search100 DSA | leetcode.com/problems/find-peak-element | Medium | nums[mid] < nums[mid-1] → peak in 0 to mid-1 | ||
| 45 | Koko Eating Bananas | Binary Search100 DSA | leetcode.com/problems/koko-eating-bananas | Medium | lo=1, hi=max(piles), check if canEat(mid) in h hours | ||
| 46 | Capacity to Ship Packages Within D Days | Binary Search100 DSA | leetcode.com/problems/capacity-to-ship-packages-within-d-days | Medium | lo=max(w), hi=sum(w), canShip(mid) in D days | ||
| 47 | Single Element in Sorted Array | Binary Search100 DSA | leetcode.com/problems/single-element-in-a-sorted-array | Medium | [odd]==[even], check where broken | ||
| 48 | Split Array Largest Sum | Binary Search100 DSA | leetcode.com/problems/split-array-largest-sum/description | Medium | Same template — minimize the max subarray sum | ||
| 49 | Allocate Books | Binary Search100 DSA | Notes | Medium | Same as Split Array Largest Sum | ||
| 50 | Find K-th Smallest Pair Distance | Binary Search100 DSA | leetcode.com/problems/find-k-th-smallest-pair-distance | Hard | lo=0, hi=max-min, count pairs with dist ≤ mid | ||
| 51 | Median of Two Sorted Arrays | Binary Search100 DSA | leetcode.com/problems/median-of-two-sorted-arrays | Hard | Make cut1, cut2 for partition | ||
| 52 | First Bad Version | Binary Search | Notes | Easy | Basic BS template | ||
| 53 | Search a 2D Matrix | Binary Search | Notes | Medium | Treat 2D as 1D: row = mid/cols, col = mid%cols | ||
| 54 | Min Days to Make m Bouquets | Binary Search | Notes | Medium | lo=1, hi=max(days), canMake(mid) m bouquets | ||
| 55 | Chess Tournament | Binary Search | Notes | Medium | Similar to allocate books | ||
| 56 | Magnetic Force Between Two Balls | Binary Search | Notes | Medium | Similar to previous | ||
| 57 | Kth Smallest in Multiplication Table | Binary Search | Notes | Medium | Count values ≤ mid using min(mid/i, n) per row | ||
| 58 | K-th Element of Two Sorted Arrays | Binary Search | Notes | Hard | Make cut1, cut2 for partition | ||
| 59 | Max Sum of Rectangle No Larger Than K | Binary Search | Notes | Hard | Iterate cols, prefix sum rows, sorted set for max ≤ K | ||
| 60 | Kadane's Algorithm | Kadane's AlgorithmPattern Template | "Maximum subarray sum", "max contiguous length" | ||||
| 61 | Maximum Subarray Sum | Kadane's Algorithm100 DSA | leetcode.com/problems/maximum-subarray/description | Medium | Kadane's — simple curMax & res | ||
| 62 | Max Circular Subarray Sum | Kadane's Algorithm100 DSA | leetcode.com/problems/maximum-sum-circular-subarray | Medium | Circular = totalSum + max(subarray of inverted array) | ||
| 63 | Monotonic Stack | Monotonic StackPattern Template | "Next greater element", "previous smaller", histogram area | ||||
| 64 | Min Stack | Monotonic Stack100 DSA | leetcode.com/problems/min-stack | Easy | |||
| 65 | Valid Parentheses | Monotonic Stack100 DSA | leetcode.com/problems/valid-parentheses | Easy | |||
| 66 | Evaluate Reverse Polish Notation | Monotonic Stack100 DSA | leetcode.com/problems/evaluate-reverse-polish-notation | Easy | |||
| 67 | Daily Temperatures | Monotonic Stack100 DSA | leetcode.com/problems/daily-temperatures | Medium | Gap between curr and nextGreater | ||
| 68 | Next Greater Element I | Monotonic Stack100 DSA | leetcode.com/problems/next-greater-element-i | Medium | Map for greater of each nums[i] | ||
| 69 | Online Stock Span | Monotonic Stack100 DSA | Notes | Medium | Stack of (price, span); pop while top.price ≤ curr | ||
| 70 | Largest Rectangle in Histogram | Monotonic Stack100 DSA | leetcode.com/problems/largest-rectangle-in-histogram | Hard | Uses prev & next smaller | ||
| 71 | Maximal Rectangle | Monotonic Stack100 DSA | leetcode.com/problems/maximal-rectangle | Hard | Histogram per row | ||
| 72 | Previous & Next Smaller | Monotonic Stack | Notes | Medium | 2 monotonic stacks | ||
| 73 | Sliding Window Maximum | Monotonic Stack | Notes | Hard | Monotonic deque — revise again | ||
| 74 | Middle of the Linked List | Linked ListFast & Slow Pointer100 DSA | Easy | slow=1, fast=2; when fast ends, slow is mid | |||
| 75 | Linked List Cycle | Linked ListFast & Slow Pointer100 DSA | leetcode.com/problems/linked-list-cycle | Medium | If fast === slow → cycle exists | ||
| 76 | Linked List Cycle II | Linked ListFast & Slow Pointer100 DSA | leetcode.com/problems/linked-list-cycle-ii/description | Medium | Floyd's: after meeting, reset one to head, move both by 1 | ||
| 77 | Remove Nth Node From End | Linked ListFast & Slow Pointer100 DSA | leetcode.com/problems/remove-nth-node-from-end-of-list/description | Medium | Move fast n steps ahead, then both until fast ends | ||
| 78 | Palindrome Linked List | Linked ListFast & Slow Pointer100 DSA | leetcode.com/problems/palindrome-linked-list | Medium | Find mid, reverse 2nd half, compare with 1st half | ||
| 79 | Find the Duplicate Number | Linked ListFast & Slow Pointer100 DSA | Notes | Medium | Floyd's on array — find cycle entry point | ||
| 80 | Delete the Middle Node | Linked ListFast & Slow Pointer | Notes | Medium | Copy next.val, move next.next | ||
| 81 | Detect Loop | Linked ListFast & Slow Pointer | Notes | Medium | Until they meet | ||
| 82 | Detect & Remove Loop | Linked ListFast & Slow Pointer | Notes | Medium | After meeting, reset slow to head, move both by 1 | ||
| 83 | Reverse Linked List | Linked ListReversal & Rearrangement100 DSA | Easy | prev=null, curr=head; curr.next=prev; shift all | |||
| 84 | Reverse Nodes in k-Group | Linked ListReversal & Rearrangement100 DSA | Notes | Hard | Count k nodes, reverse that segment, connect to next | ||
| 85 | Swap Nodes in Pairs | Linked ListReversal & Rearrangement | Notes | Medium | Swap last pair, use head for previous | ||
| 86 | Odd Even Linked List | Linked ListReversal & Rearrangement | Notes | Medium | 4 pointers: oE, oS, eS, eE | ||
| 87 | Reorder List | Linked ListReversal & Rearrangement100 DSA | leetcode.com/problems/reorder-list | Easy | |||
| 88 | Rotate List | Linked ListReversal & Rearrangement | Notes | Medium | Find length, k=k%len, connect tail to head, break at len-k | ||
| 89 | Merge Two Sorted Lists | Linked ListMerge & Other100 DSA | leetcode.com/problems/merge-two-sorted-lists | Medium | Compare heads, attach smaller, advance | ||
| 90 | Add Two Numbers | Linked ListMerge & Other100 DSA | leetcode.com/problems/add-two-numbers | Medium | Traverse both, sum digits + carry, carry = sum/10 | ||
| 91 | Remove Duplicates from Sorted List | Linked ListMerge & Other | Notes | Easy | Check and delete pointer | ||
| 92 | Delete Node in a Linked List | Linked ListMerge & Other | Notes | Easy | Assign next's val and next | ||
| 93 | Remove Linked List Elements | Linked ListMerge & Other | Notes | Easy | Remove initial vals, then find and skip | ||
| 94 | Intersection of Two Linked Lists | Linked ListMerge & Other | Notes | Medium | Loop both until meet, reset to each other's head | ||
| 95 | Union & Intersection of Linked Lists | Linked ListMerge & Other | Notes | Medium | Insert L1 in set, check L2 | ||
| 96 | Maximum Depth | Trees & BSTDFS - Traversal & Height100 DSA | leetcode.com/problems/maximum-depth-of-binary-tree | Easy | Recursively check left & right + 1 | ||
| 97 | Inorder Traversal | Trees & BSTDFS - Traversal & Height100 DSA | leetcode.com/problems/binary-tree-inorder-traversal | Easy | left, push, right. Learn stack version too | ||
| 98 | Preorder Traversal | Trees & BSTDFS - Traversal & Height100 DSA | leetcode.com/problems/binary-tree-preorder-traversal | Easy | push, left, right | ||
| 99 | Postorder Traversal | Trees & BSTDFS - Traversal & Height100 DSA | leetcode.com/problems/binary-tree-postorder-traversal | Easy | left, right, push | ||
| 100 | Same Tree | Trees & BSTDFS - Traversal & Height100 DSA | leetcode.com/problems/same-tree | Easy | Recursively check val, left, right; both null → true |
Showing the first 100 of 336 rows.