Coding interview problems
3,736 problems: 937 Easy, 1,914 Medium, 885 Hard. Each runs against hidden tests, in 13 languages; database problems in SQL. Free for members.
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Problems 101–200 of 3,736
- 101. Product of the Others Medium · Array, Prefix Sum
- 102. Next Arrangement Up Medium · Array, Two Pointers
- 103. Seen Exactly Twice Medium · Array, Hash Table
- 104. The Repeated Value Medium · Array, Two Pointers, Binary Search, Bit Manipulation
- 105. Three-Colour Sort Medium · Array, Two Pointers, Sorting
- 106. Votes Over a Third Medium · Array, Hash Table, Counting, Sorting
- 107. Researcher Impact Score Medium · Array, Sorting, Counting
- 108. Fuel Stop Loop Medium · Array, Greedy
- 109. Parse a Whole Number Medium · String
- 110. Number to Roman Numeral Medium · String, Hash Table, Math
- 111. Long Multiplication on Strings Medium · String, Math, Simulation
- 112. Compare Release Tags Medium · String, Two Pointers
- 113. Tidy a File Path Medium · String, Stack
- 114. Longest Mirror Substring Medium · String, Dynamic Programming, Two Pointers
- 115. Count Mirror Substrings Medium · String, Dynamic Programming, Two Pointers
- 116. Nine-by-Nine Board Check Medium · Array, Hash Table, Matrix · 100% accepted
- 117. Count the Fleets Medium · Array, Matrix, Depth-First Search
- 118. Reveal the Field Medium · Array, Matrix, Depth-First Search, Breadth-First Search
- 119. Reachable Noughts Board Medium · Array, Matrix, String
- 120. Crush the Candy Board Medium · Array, Matrix, Two Pointers, Simulation
- 121. Sort Each Diagonal Medium · Array, Matrix, Sorting
- 122. Neighbourhood Totals Medium · Array, Matrix, Prefix Sum
- 123. Count All-Ones Squares Medium · Array, Matrix, Dynamic Programming
- 124. Longest Ones Line in Any Direction Medium · Array, Matrix, Dynamic Programming
- 125. Cut Through the Fewest Bricks Medium · Array, Hash Table
- 126. Range Letter Shifts Medium · String, Prefix Sum, Array
- 127. Split Into Letter Zones Medium · String, Greedy, Two Pointers, Hash Table
- 128. Fewest Pieces With Unique Letters Medium · String, Greedy, Hash Table
- 129. No Twin Neighbours Medium · String, Greedy, Heap (Priority Queue), Counting
- 130. Alphabet by House Rules Medium · String, Hash Table, Sorting
- 131. Letters by Popularity Medium · String, Hash Table, Sorting, Counting
- 132. Dense Rank Labels Medium · Array, Hash Table, Sorting
- 133. Up-Down Shuffle Medium · Array, Greedy, Sorting
- 134. Alternate Gains and Losses Medium · Array, Two Pointers, Simulation
- 135. Spatula Sort Medium · Array, Two Pointers, Greedy, Sorting
- 136. Make Badge Numbers Unique Medium · Array, Greedy, Sorting, Counting
- 137. Longest Index Loop Medium · Array, Depth-First Search
- 138. Fewest Swaps to Sort Medium · Array, Sorting, Graph
- 139. Exactly k Distinct Step Sizes Medium · Array, Math
- 140. Windows With a Peak in Bounds Medium · Array, Two Pointers
- 141. Sortable Blocks Medium · Array, Greedy
- 142. Longest Hill Medium · Array, Two Pointers, Dynamic Programming
- 143. Longest Seesaw Run Medium · Array, Dynamic Programming, Sliding Window
- 144. Shortest Window to Fix Medium · Array, Two Pointers, Sorting, Monotonic Stack
- 145. Widest Sorted Gap Medium · Array, Sorting
- 146. Line Up by the Taller Count Medium · Array, Greedy, Sorting
- 147. Toppling Tiles Medium · String, Two Pointers, Dynamic Programming, Simulation
- 148. Codebreaker Feedback Medium · String, Hash Table, Counting
- 149. Replace at Positions Medium · String, Array, Sorting
- 150. Stretchy Greetings Medium · String, Two Pointers
- 151. One Edit Apart Medium · String, Two Pointers
- 152. Make a Dice Row Uniform Medium · Array, Greedy
- 153. One Swap Smaller Medium · Array, Greedy
- 154. Next Number With the Same Digits Medium · Math, String, Two Pointers
- 155. Best Single Digit Swap Medium · Math, Greedy
- 156. Latest Clock From Four Digits Medium · Array, String, Math
- 157. Repeating Decimal Text Medium · Math, String, Hash Table
- 158. Complex Product Text Easy · Math, String
- 159. Fraction Chain Sum Medium · Math, String, Simulation
- 160. Solve for x Medium · String, Math, Simulation
- 161. What Kind of Address? Medium · String
- 162. Say What You See Medium · String, Simulation
- 163. Character in the Expanded Tape Medium · String, Stack
- 164. Bold the Keywords Medium · String, Array, Hash Table, Intervals
- 165. Windows With an Odd Total Medium · Array, Prefix Sum, Math, Dynamic Programming
- 166. All-Zero Stretches Medium · Array, Math
- 167. Meet at the Median Medium · Array, Sorting, Math
- 168. Raise All but One Medium · Array, Math
- 169. Longest Wobble Medium · Array, Greedy, Dynamic Programming
- 170. Pair Each With Its Double Medium · Array, Hash Table, Greedy, Sorting
- 171. Fewest Edits to Alternate Medium · Array, Hash Table, Counting, Greedy
- 172. Deal Into Straights Medium · Array, Hash Table, Greedy, Sorting
- 173. Pattern Repeated k Times Medium · Array
- 174. Split Into Ladders Medium · Array, Hash Table, Greedy, Heap (Priority Queue)
- 175. Distinct ORs of Subarrays Medium · Array, Bit Manipulation, Dynamic Programming
- 176. Make Letter Tallies Distinct Medium · String, Greedy, Sorting, Hash Table
- 177. Largest Plus in a Field Medium · Array, Matrix, Dynamic Programming
- 178. Fewest Replacements to an Anagram Medium · String, Hash Table, Counting
- 179. Build the Target With Two Ops Medium · Array, Greedy, Bit Manipulation
- 180. Off-by-One Substring Pairs Medium · String, Hash Table, Dynamic Programming
- 181. Smallest by Same-Parity Swaps Easy · String, Sorting
- 182. Split in Three With Equal Ones Medium · String, Math
- 183. Reverse Every k-Block Easy · String, Two Pointers
- 184. Fewest Flips to Rising Bits Medium · String, Dynamic Programming, Prefix Sum
- 185. Prefix-and-Suffix Word Pairs Medium · String, Array, Trie, Hash Table
- 186. Slide L and R Medium · String, Two Pointers
- 187. Shortest Run to Light Every Channel Medium · Array, Bit Manipulation, Sliding Window
- 188. Banner Repeats on a Screen Medium · String, Dynamic Programming, Simulation
- 189. Richest Window of Distinct Prices Medium · Array, Hash Table, Sliding Window
- 190. Undo the Brackets Medium · String, Stack
- 191. Longest Unshared Subsequence Medium · String, Hash Table, Sorting
- 192. DNA Complement Mirrors Medium · String, Two Pointers, Dynamic Programming
- 193. How Many Are Hidden Inside? Medium · String, Hash Table, Binary Search, Trie
- 194. Fewest Copies to Spell Medium · String, Greedy, Two Pointers
- 195. Spoken Number Words Hard · String, Math, Recursion
- 196. Capital Pattern Queries Medium · String, Two Pointers, Trie
- 197. Read Down the Columns Medium · String, Array, Simulation
- 198. Files With Twin Contents Medium · String, Hash Table
- 199. Domain Visit Tally Medium · String, Hash Table, Counting
- 200. Sort the Journal Medium · String, Sorting
