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These are the most popular coding interview question from easy to hard in order.

The problem covers common pattern / algo in interview:

• Binary search
• Two pointers
• Backtracking
• DFS
• BFS
• Dynamic programming
• Stack / Greedy / Heap
• Swap corresponding values
• Store one or more different values in the same pointer
• Trie / Map

Reference :

14 Patterns to Ace Any Coding Interview Question https://hackernoon.com/14-patterns-to-ace-any-coding-interview-question-c5bb3357f6ed

Coding Interview Question

• 1 Contains Duplicate https://leetcode.com/problems/contains-duplicate/
• 2 Missing Number https://leetcode.com/problems/missing-number/
• 3 Find All Numbers Disappeared in an Array https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/
• 4 Single Number https://leetcode.com/problems/single-number/
• 5 Climbing Stairs https://leetcode.com/problems/climbing-stairs/
• 6 Best Time to Buy and Sell Stock https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
• 7 Maximum Subarray https://leetcode.com/problems/maximum-subarray/
• 8 Range Sum Query - Immutable https://leetcode.com/problems/range-sum-query-immutable/
• 9 Linked List Cycle https://leetcode.com/problems/linked-list-cycle/
• 10 Middle of the Linked List https://leetcode.com/problems/middle-of-the-linked-list/
• 11 Palindrome Linked List https://leetcode.com/problems/palindrome-linked-list/
• 12 Remove Linked List Elements https://leetcode.com/problems/remove-linked-list-elements/
• 13 Remove Duplicates from Sorted List https://leetcode.com/problems/remove-duplicates-from-sorted-list/
• 14 Reverse Linked List https://leetcode.com/problems/reverse-linked-list/
• 15 Merge Two Sorted Lists https://leetcode.com/problems/merge-two-sorted-lists/
• 16 Meeting Rooms https://leetcode.com/problems/meeting-rooms
• 17 Binary Search https://leetcode.com/problems/binary-search/
• 18 Find Smallest Letter Greater Than Target https://leetcode.com/problems/find-smallest-letter-greater-than-target/
• 19 Peak Index in a Mountain Array https://leetcode.com/problems/peak-index-in-a-mountain-array/
• 20 Binary Tree Level Order Traversal II https://leetcode.com/problems/binary-tree-level-order-traversal-ii/
• 21 Average of Levels in Binary Tree https://leetcode.com/problems/average-of-levels-in-binary-tree/
• 22 Minimum Depth of Binary Tree https://leetcode.com/problems/minimum-depth-of-binary-tree/
• 23 Same Tree https://leetcode.com/problems/same-tree/
• 24 Path Sum https://leetcode.com/problems/path-sum/
• 25 Diameter of Binary Tree https://leetcode.com/problems/diameter-of-binary-tree/
• 26 Merge Two Binary Trees https://leetcode.com/problems/merge-two-binary-trees/
• 27 Maximum Depth of Binary Tree https://leetcode.com/problems/maximum-depth-of-binary-tree/
• 28 Lowest Common Ancestor of a Binary Search Tree https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/
• 29 Subtree of Another Tree https://leetcode.com/problems/subtree-of-another-tree/
• 30 Invert Binary Tree https://leetcode.com/problems/invert-binary-tree/
• 31 Two Sum https://leetcode.com/problems/two-sum/
• 32 Squares of a Sorted Array https://leetcode.com/problems/squares-of-a-sorted-array/
• 33 Backspace String Compare https://leetcode.com/problems/backspace-string-compare
• 34 Longest Word in Dictionary https://leetcode.com/problems/longest-word-in-dictionary/
• 35 Index Pairs of a String https://leetcode.com/problems/index-pairs-of-a-string/
• 36 Majority Element https://leetcode.com/problems/majority-element/
• 37 Product of Array Except Self https://leetcode.com/problems/product-of-array-except-self/
• 38 Find the Duplicate Number https://leetcode.com/problems/find-the-duplicate-number/
• 39 Find All Duplicates in an Array https://leetcode.com/problems/find-all-duplicates-in-an-array/
• 40 Set Matrix Zeroes https://leetcode.com/problems/set-matrix-zeroes/
• 41 Spiral Matrix https://leetcode.com/problems/spiral-matrix/
• 42 Rotate Image https://leetcode.com/problems/rotate-image/
• 43 Word Search https://leetcode.com/problems/word-search/
• 44 Letter Case Permutation https://leetcode.com/problems/letter-case-permutation/
• 45 Subsets https://leetcode.com/problems/subsets/
• 46 Subsets II https://leetcode.com/problems/subsets-ii/
• 47 Permutations https://leetcode.com/problems/permutations/
• 48 Permutations II https://leetcode.com/problems/permutations-ii/
• 49 Combinations https://leetcode.com/problems/combinations/
• 50 Combination Sum https://leetcode.com/problems/combination-sum/
• 51 Combination Sum II https://leetcode.com/problems/combination-sum-ii/
• 52 Combination Sum III https://leetcode.com/problems/combination-sum-iii/
• 53 Generate Parentheses https://leetcode.com/problems/generate-parentheses/
• 54 Target Sum https://leetcode.com/problems/target-sum/
• 55 Palindrome Partitioning https://leetcode.com/problems/palindrome-partitioning/
• 56 Letter Combinations of a Phone Number https://leetcode.com/problems/letter-combinations-of-a-phone-number/
• 57 Generalized Abbreviation https://leetcode.com/problems/generalized-abbreviation/
• 58 House Robber https://leetcode.com/problems/house-robber/
• 59 House Robber II https://leetcode.com/problems/house-robber-ii/
• 60 Coin Change https://leetcode.com/problems/coin-change/
• 61 Maximum Product Subarray https://leetcode.com/problems/maximum-product-subarray/
• 62 Longest Increasing Subsequence https://leetcode.com/problems/longest-increasing-subsequence/
• 63 Longest Palindromic Substring https://leetcode.com/problems/longest-palindromic-substring/
• 64 Word Break https://leetcode.com/problems/word-break/
• 65 Combination Sum IV https://leetcode.com/problems/combination-sum-iv/
• 66 Decode Ways https://leetcode.com/problems/decode-ways/
• 67 Unique Paths https://leetcode.com/problems/unique-paths/
• 68 Jump Game https://leetcode.com/problems/jump-game/
• 69 Palindromic Substrings https://leetcode.com/problems/palindromic-substrings/
• 70 Number of Longest Increasing Subsequence https://leetcode.com/problems/number-of-longest-increasing-subsequence/
• 71 Partition Equal Subset Sum https://leetcode.com/problems/partition-equal-subset-sum/
• 72 Partition to K Equal Sum Subsets https://leetcode.com/problems/partition-to-k-equal-sum-subsets/
• 73 Best Time to Buy and Sell Stock with Cooldown https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown/
• 74 Counting Bits https://leetcode.com/problems/counting-bits/
• 75 Linked List Cycle II https://leetcode.com/problems/linked-list-cycle-ii/
• 76 Add Two Numbers https://leetcode.com/problems/add-two-numbers/
• 77 Remove Nth Node From End Of List https://leetcode.com/problems/remove-nth-node-from-end-of-list/
• 78 Sort List https://leetcode.com/problems/sort-list/
• 79 Reorder List https://leetcode.com/problems/reorder-list/
• 80 Clone Graph https://leetcode.com/problems/clone-graph/
• 81 Pacific Atlantic Water Flow https://leetcode.com/problems/pacific-atlantic-water-flow/
• 82 Number of Islands https://leetcode.com/problems/number-of-islands/
• 83 Graph Valid Tree https://leetcode.com/problems/graph-valid-tree/
• 84 Number of Connected Components in an Undirected Graph https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/
• 85 Reverse Linked List II https://leetcode.com/problems/reverse-linked-list-ii/
• 86 Rotate List https://leetcode.com/problems/rotate-list/
• 87 Swap Nodes in Pairs https://leetcode.com/problems/swap-nodes-in-pairs/
• 88 Odd Even Linked List https://leetcode.com/problems/odd-even-linked-list/
• 89 Kth Smallest Element in a Sorted Matrix https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/
• 90 Find K Pairs with Smallest Sums https://leetcode.com/problems/find-k-pairs-with-smallest-sums/
• 91 Merge Intervals https://leetcode.com/problems/merge-intervals/
• 92 Interval List Intersections https://leetcode.com/problems/interval-list-intersections/
• 93 Non-overlapping Intervals https://leetcode.com/problems/non-overlapping-intervals/
• 94 Meeting Rooms II https://leetcode.com/problems/meeting-rooms-ii/
• 95 Task Scheduler https://leetcode.com/problems/task-scheduler/
• 96 Minimum Number of Arrows to Burst Balloons https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons/
• 97 Find Minimum in Rotated Sorted Array https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/
• 98 Find Peak Element https://leetcode.com/problems/find-peak-element/
• 99 Search in Rotated Sorted Array https://leetcode.com/problems/search-in-rotated-sorted-array/
• 100 Search in Rotated Sorted Array II https://leetcode.com/problems/search-in-rotated-sorted-array-ii/
• 101 Search a 2D Matrix https://leetcode.com/problems/search-a-2d-matrix/
• 102 Search a 2D Matrix II https://leetcode.com/problems/search-a-2d-matrix-ii/
• 103 Find K Closest Elements https://leetcode.com/problems/find-k-closest-elements/
• 104 Minimum Size Subarray Sum https://leetcode.com/problems/minimum-size-subarray-sum/
• 105 Fruit Into Baskets https://leetcode.com/problems/fruit-into-baskets/
• 106 Permutation in String https://leetcode.com/problems/permutation-in-string/
• 107 Longest Repeating Character Replacement https://leetcode.com/problems/longest-repeating-character-replacement/
• 108 Kth Smallest Element in a BST https://leetcode.com/problems/kth-smallest-element-in-a-bst/
• 109 K Closest Points to Origin https://leetcode.com/problems/k-closest-points-to-origin/
• 110 Top K Frequent Elements https://leetcode.com/problems/top-k-frequent-elements/
• 111 Sort Characters By Frequency https://leetcode.com/problems/sort-characters-by-frequency/
• 112 Kth Largest Element in an Array https://leetcode.com/problems/kth-largest-element-in-an-array/
• 113 Reorganize String https://leetcode.com/problems/reorganize-string/
• 114 Course Schedule https://leetcode.com/problems/course-schedule/
• 115 Course Schedule II https://leetcode.com/problems/course-schedule-ii/
• 116 Minimum Height Trees https://leetcode.com/problems/minimum-height-trees/
• 117 Binary Tree Level Order Traversal https://leetcode.com/problems/binary-tree-level-order-traversal/
• 118 Binary Tree Zigzag Level Order Traversal https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/
• 119 Populating Next Right Pointers in Each Node https://leetcode.com/problems/populating-next-right-pointers-in-each-node/
• 120 Populating Next Right Pointers in Each Node II https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/
• 121 Binary Tree Right Side View https://leetcode.com/problems/binary-tree-right-side-view/
• 122 All Nodes Distance K in Binary Tree https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree/
• 123 Path Sum II https://leetcode.com/problems/path-sum-ii/
• 124 Path Sum III https://leetcode.com/problems/path-sum-iii/
• 125 Lowest Common Ancestor of a Binary Tree https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/
• 126 Maximum Binary Tree https://leetcode.com/problems/maximum-binary-tree/
• 127 Maximum Width of Binary Tree https://leetcode.com/problems/maximum-width-of-binary-tree/
• 128 Construct Binary Tree from Preorder and Inorder Traversal https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/
• 129 Validate Binary Search Tree https://leetcode.com/problems/validate-binary-search-tree/
• 130 Implement Trie (Prefix Tree) https://leetcode.com/problems/implement-trie-prefix-tree/
• 131 3 Sum https://leetcode.com/problems/3sum/
• 132 3 Sum Closest https://leetcode.com/problems/3sum-closest/
• 133 Subarrays with Product Less than K https://leetcode.com/problems/subarray-product-less-than-k/
• 134 Sort Colours https://leetcode.com/problems/sort-colors/
• 135 Maximum XOR of Two Numbers in an Array https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array
• 136 First Missing Positive https://leetcode.com/problems/first-missing-positive/
• 137 Longest Consecutive Sequence https://leetcode.com/problems/longest-consecutive-sequence/
• 138 Sudoku Solver https://leetcode.com/problems/sudoku-solver/
• 139 N-Queens https://leetcode.com/problems/n-queens/
• 140 Reverse Nodes in k-Group https://leetcode.com/problems/reverse-nodes-in-k-group/
• 141 Merge k Sorted Lists https://leetcode.com/problems/merge-k-sorted-lists/
• 142 Smallest Range Covering Elements from K Lists https://leetcode.com/problems/smallest-range-covering-elements-from-k-lists/
• 143 Insert Interval https://leetcode.com/problems/insert-interval/
• 144 Employee Free Time https://leetcode.com/problems/employee-free-time/
• 145 Count of Range Sum https://leetcode.com/problems/count-of-range-sum/
• 146 Sliding Window Maximum https://leetcode.com/problems/sliding-window-maximum/
• 147 Longest Substring Without Repeating Characters https://leetcode.com/problems/longest-substring-without-repeating-characters/
• 148 Minimum Number of K Consecutive Bit Flips https://leetcode.com/problems/minimum-number-of-k-consecutive-bit-flips/
• 149 Count Unique Characters of All Substrings of a Given String https://leetcode.com/problems/count-unique-characters-of-all-substrings-of-a-given-string/
• 150 Minimum Window Substring https://leetcode.com/problems/minimum-window-substring/
• 151 Substring with Concatenation of All Words https://leetcode.com/problems/substring-with-concatenation-of-all-words/
• 152 Rearrange String k Distance Apart https://leetcode.com/problems/rearrange-string-k-distance-apart
• 153 Course Schedule III https://leetcode.com/problems/course-schedule-iii/
• 154 Maximum Frequency Stack https://leetcode.com/problems/maximum-frequency-stack/
• 155 Alien Dictionary https://leetcode.com/problems/alien-dictionary
• 156 Sequence Reconstruction https://leetcode.com/problems/sequence-reconstruction
• 157 Binary Tree Maximum Path Sum https://leetcode.com/problems/binary-tree-maximum-path-sum/
• 158 Serialize and Deserialize Binary Tree https://leetcode.com/problems/serialize-and-deserialize-binary-tree/
• 159 Word Search II https://leetcode.com/problems/word-search-ii/
• 160 Find Median from Data Stream https://leetcode.com/problems/find-median-from-data-stream/
• 161 Sliding Window Median https://leetcode.com/problems/sliding-window-median/
• 162 Trapping Rain Water https://leetcode.com/problems/trapping-rain-water/
• 163 Container With Most Water https://leetcode.com/problems/container-with-most-water/
• 164 Concatenated Words https://leetcode.com/problems/concatenated-words/
• 165 Prefix and Suffix Search https://leetcode.com/problems/prefix-and-suffix-search/
• 166 Palindrome Pairs https://leetcode.com/problems/palindrome-pairs/
• 167 Design Search Autocomplete System https://leetcode.com/problems/design-search-autocomplete-system/
• 168 Word Squares https://leetcode.com/problems/word-squares/
• 169 Sort Items by Groups Respecting Dependencies https://leetcode.com/problems/sort-items-by-groups-respecting-dependencies/
• 170 Median of Two Sorted Arrays https://leetcode.com/problems/median-of-two-sorted-arrays/

Additional Questions

• Sub Array Sub K https://leetcode.com/problems/subarray-sum-equals-k/

Question by Concept

Arrays

• Contains Duplicate https://leetcode.com/problems/contains-duplicate/
• Missing Number https://leetcode.com/problems/missing-number/
• Find All Numbers Disappeared in an Array https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/
• Single Number https://leetcode.com/problems/single-number/
• Product of Array Except Self https://leetcode.com/problems/product-of-array-except-self/
• Find the Duplicate Number https://leetcode.com/problems/find-the-duplicate-number/
• Find All Duplicates in an Array https://leetcode.com/problems/find-all-duplicates-in-an-array/
• Set Matrix Zeroes https://leetcode.com/problems/set-matrix-zeroes/
• Spiral Matrix https://leetcode.com/problems/spiral-matrix/
• Rotate Image https://leetcode.com/problems/rotate-image/
• First Missing Positive https://leetcode.com/problems/first-missing-positive/
• Longest Consecutive Sequence https://leetcode.com/problems/longest-consecutive-sequence/

Binary Search

• Binary Search https://leetcode.com/problems/binary-search/
• Find Smallest Letter Greater Than Target https://leetcode.com/problems/find-smallest-letter-greater-than-target/
• Peak Index in a Mountain Array https://leetcode.com/problems/peak-index-in-a-mountain-array/
• Find the Duplicate Number https://leetcode.com/problems/find-the-duplicate-number/
• Kth Smallest Element in a Sorted Matrix https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/
• Find Minimum in Rotated Sorted Array https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/
• Find Peak Element https://leetcode.com/problems/find-peak-element/
• Search in Rotated Sorted Array https://leetcode.com/problems/search-in-rotated-sorted-array/
• Search in Rotated Sorted Array II https://leetcode.com/problems/search-in-rotated-sorted-array-ii/
• Search a 2D Matrix https://leetcode.com/problems/search-a-2d-matrix/
• Search a 2D Matrix II https://leetcode.com/problems/search-a-2d-matrix-ii/
• Find K Closest Elements https://leetcode.com/problems/find-k-closest-elements/
• Count of Range Sum https://leetcode.com/problems/count-of-range-sum/
• Median of Two Sorted Arrays https://leetcode.com/problems/median-of-two-sorted-arrays/

Backtracking

• Word Search https://leetcode.com/problems/word-search/
• Letter Case Permutation https://leetcode.com/problems/letter-case-permutation/
• Subsets https://leetcode.com/problems/subsets/
• Subsets II https://leetcode.com/problems/subsets-ii/
• Permutations https://leetcode.com/problems/permutations/* Binary Search https://leetcode.com/problems/binary-search/
• Find Smallest Letter Greater Than Target https://leetcode.com/problems/find-smallest-letter-greater-than-target/
• Peak Index in a Mountain Array https://leetcode.com/problems/peak-index-in-a-mountain-array/
• Find the Duplicate Number https://leetcode.com/problems/find-the-duplicate-number/
• Kth Smallest Element in a Sorted Matrix https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/
• Find Minimum in Rotated Sorted Array https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/
• Find Peak Element https://leetcode.com/problems/find-peak-element/
• Search in Rotated Sorted Array https://leetcode.com/problems/search-in-rotated-sorted-array/
• Search in Rotated Sorted Array II https://leetcode.com/problems/search-in-rotated-sorted-array-ii/
• Search a 2D Matrix https://leetcode.com/problems/search-a-2d-matrix/
• Search a 2D Matrix II https://leetcode.com/problems/search-a-2d-matrix-ii/
• Find K Closest Elements https://leetcode.com/problems/find-k-closest-elements/
• Count of Range Sum https://leetcode.com/problems/count-of-range-sum/
• Median of Two Sorted Arrays https://leetcode.com/problems/median-of-two-sorted-arrays/
• Permutations II https://leetcode.com/problems/permutations-ii/
• Combinations https://leetcode.com/problems/combinations/
• Combination Sum https://leetcode.com/problems/combination-sum/
• Combination Sum II https://leetcode.com/problems/combination-sum-ii/
• Combination Sum III https://leetcode.com/problems/combination-sum-iii/
• Generate Parentheses https://leetcode.com/problems/generate-parentheses/
• Palindrome Partitioning https://leetcode.com/problems/palindrome-partitioning/
• Letter Combinations of a Phone Number https://leetcode.com/problems/letter-combinations-of-a-phone-number/
• Generalized Abbreviation https://leetcode.com/problems/generalized-abbreviation/
• Sudoku Solver https://leetcode.com/problems/sudoku-solver/
• N-Queens https://leetcode.com/problems/n-queens/

Graph / Tree Search (BFS/DFS)

• Binary Tree Level Order Traversal II https://leetcode.com/problems/binary-tree-level-order-traversal-ii/
• Average of Levels in Binary Tree https://leetcode.com/problems/average-of-levels-in-binary-tree/
• Minimum Depth of Binary Tree https://leetcode.com/problems/minimum-depth-of-binary-tree/
• Same Tree https://leetcode.com/problems/same-tree/
• Path Sum https://leetcode.com/problems/path-sum/
• Clone Graph https://leetcode.com/problems/clone-graph/
• Merge Two Binary Trees https://leetcode.com/problems/merge-two-binary-trees/
• Pacific Atlantic Water Flow https://leetcode.com/problems/pacific-atlantic-water-flow/
• Number of Islands https://leetcode.com/problems/number-of-islands/
• Graph Valid Tree https://leetcode.com/problems/graph-valid-tree/
• Maximum Depth of Binary Tree https://leetcode.com/problems/maximum-depth-of-binary-tree/
• Lowest Common Ancestor of a Binary Search Tree https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/
• Subtree of Another Tree https://leetcode.com/problems/subtree-of-another-tree/
• Invert Binary Tree https://leetcode.com/problems/invert-binary-tree/
• Target Sum https://leetcode.com/problems/target-sum/
• Clone Graph https://leetcode.com/problems/clone-graph/
• Pacific Atlantic Water Flow https://leetcode.com/problems/pacific-atlantic-water-flow/
• Number of Islands https://leetcode.com/problems/number-of-islands/
• Number of Connected Components in an Undirected Graph https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/
• Kth Smallest Element in a BST https://leetcode.com/problems/kth-smallest-element-in-a-bst/
• Binary Tree Right Side View https://leetcode.com/problems/binary-tree-right-side-view/
• All Nodes Distance K in Binary Tree https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree/
• Path Sum II https://leetcode.com/problems/path-sum-ii/
• Path Sum III https://leetcode.com/problems/path-sum-iii/
• Lowest Common Ancestor of a Binary Tree https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/
• Number of Connected Components in an Undirected Graph https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/
• Course Schedule https://leetcode.com/problems/course-schedule/
• Course Schedule II https://leetcode.com/problems/course-schedule-ii/
• Minimum Height Trees https://leetcode.com/problems/minimum-height-trees/
• Binary Tree Level Order Traversal https://leetcode.com/problems/binary-tree-level-order-traversal/
• Binary Tree Zigzag Level Order Traversal https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/
• Validate Binary Search Tree https://leetcode.com/problems/validate-binary-search-tree/
• Maximum Width of Binary Tree https://leetcode.com/problems/maximum-width-of-binary-tree/
• Populating Next Right Pointers in Each Node https://leetcode.com/problems/populating-next-right-pointers-in-each-node/
• Populating Next Right Pointers in Each Node II https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/
• Binary Tree Right Side View https://leetcode.com/problems/binary-tree-right-side-view/
• Binary Tree Maximum Path Sum https://leetcode.com/problems/binary-tree-maximum-path-sum/
• Construct Binary Tree from Preorder and Inorder Traversal https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/
• All Nodes Distance K in Binary Tree https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree/
• Word Search II https://leetcode.com/problems/word-search-ii/
• Sort Items by Groups Respecting Dependencies https://leetcode.com/problems/sort-items-by-groups-respecting-dependencies/

Trie

• Longest Word in Dictionary https://leetcode.com/problems/longest-word-in-dictionary/
• Index Pairs of a String https://leetcode.com/problems/index-pairs-of-a-string/
• Implement Trie (Prefix Tree) https://leetcode.com/problems/implement-trie-prefix-tree/
• Maximum XOR of Two Numbers in an Array https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array
• Word Search II https://leetcode.com/problems/word-search-ii/
• Concatenated Words https://leetcode.com/problems/concatenated-words/
• Prefix and Suffix Search https://leetcode.com/problems/prefix-and-suffix-search/
• Palindrome Pairs https://leetcode.com/problems/palindrome-pairs/
• Design Search Autocomplete System https://leetcode.com/problems/design-search-autocomplete-system/
• Word Squares https://leetcode.com/problems/word-squares/