| Number of Subarrays That Match a Pattern I | Open ↗ |
| Number of Subarrays That Match a Pattern II | Open ↗ |
| Number of Subarrays With AND Value of K | Open ↗ |
| Number of Subarrays with Bounded Maximum | Open ↗ |
| Number of Subarrays With LCM Equal to K | Open ↗ |
| Number of Sub-arrays With Odd Sum | Open ↗ |
| Number of Submatrices That Sum to Target | Open ↗ |
| Number of Subsequences That Satisfy the Given Sum Condition | Open ↗ |
| Number of Substrings Containing All Three Characters | Open ↗ |
| Number of Substrings With Fixed Ratio | Open ↗ |
| Number of Substrings With Only 1s | Open ↗ |
| Number of Times a Driver Was a Passenger | Open ↗ |
| Number of Times Binary String Is Prefix-Aligned | Open ↗ |
| Number of Transactions per Visit | Open ↗ |
| Number of Trusted Contacts of a Customer | Open ↗ |
| Number of Unequal Triplets in Array | Open ↗ |
| Number of Unique Categories | Open ↗ |
| Number of Unique Flavors After Sharing K Candies | Open ↗ |
| Number of Unique Good Subsequences | Open ↗ |
| Number of Unique Subjects Taught by Each Teacher | Open ↗ |
| Number of Unique XOR Triplets I | Open ↗ |
| Number of Unique XOR Triplets II | Open ↗ |
| Number of Valid Clock Times | Open ↗ |
| Number of Valid Move Combinations On Chessboard | Open ↗ |
| Number of Valid Subarrays | Open ↗ |
| Number of Valid Words for Each Puzzle | Open ↗ |
| Number of Valid Words in a Sentence | Open ↗ |
| Number of Visible People in a Queue | Open ↗ |
| Number of Ways of Cutting a Pizza | Open ↗ |
| Number of Ways to Arrive at Destination | Open ↗ |
| Number of Ways to Assign Edge Weights I | Open ↗ |
| Number of Ways to Assign Edge Weights II | Open ↗ |
| Number of Ways to Build House of Cards | Open ↗ |
| Number of Ways to Build Sturdy Brick Wall | Open ↗ |
| Number of Ways to Buy Pens and Pencils | Open ↗ |
| Number of Ways to Divide a Long Corridor | Open ↗ |
| Number of Ways to Earn Points | Open ↗ |
| Number of Ways to Form a Target String Given a Dictionary | Open ↗ |
| Number of Ways to Paint N × 3 Grid | Open ↗ |
| Number of Ways to Reach a Position After Exactly k Steps | Open ↗ |
| Number of Ways to Reach Destination in the Grid | Open ↗ |
| Number of Ways to Rearrange Sticks With K Sticks Visible | Open ↗ |
| Number Of Ways To Reconstruct A Tree | Open ↗ |
| Number of Ways to Reorder Array to Get Same BST | Open ↗ |
| Number of Ways to Select Buildings | Open ↗ |
| Number of Ways to Separate Numbers | Open ↗ |
| Number of Ways to Split Array | Open ↗ |
| Number of Ways to Split a String | Open ↗ |
| Number of Ways to Stay in the Same Place After Some Steps | Open ↗ |
| Number of Ways to Wear Different Hats to Each Other | Open ↗ |
| Number of Wonderful Substrings | Open ↗ |
| Number of Zero-Filled Subarrays | Open ↗ |
| Number of ZigZag Arrays I | Open ↗ |
| Number of ZigZag Arrays II | Open ↗ |
| Numbers At Most N Given Digit Set | Open ↗ |
| Numbers With Repeated Digits | Open ↗ |
| Numbers With Same Consecutive Differences | Open ↗ |
| Occurrences After Bigram | Open ↗ |
| Odd and Even Transactions | Open ↗ |
| Odd Even Jump | Open ↗ |
| Odd Even Linked List | Open ↗ |
| Odd String Difference | Open ↗ |
| One Edit Distance | Open ↗ |
| Ones and Zeroes | Open ↗ |
| Online Election | Open ↗ |
| Online Majority Element In Subarray | Open ↗ |
| Online Stock Span | Open ↗ |
| Open the Lock | Open ↗ |
| Operations on Tree | Open ↗ |
| Optimal Account Balancing | Open ↗ |
| Optimal Division | Open ↗ |
| Optimal Partition of String | Open ↗ |
| Optimize Water Distribution in a Village | Open ↗ |
| Orderly Queue | Open ↗ |
| Order Two Columns Independently | Open ↗ |
| Out of Boundary Paths | Open ↗ |
| Output Contest Matches | Open ↗ |
| Pacific Atlantic Water Flow | Open ↗ |
| Page Recommendations | Open ↗ |
| Page Recommendations II | Open ↗ |
| Paint Fence | Open ↗ |
| Paint House | Open ↗ |
| Paint House II | Open ↗ |
| Paint House III | Open ↗ |
| Paint House IV | Open ↗ |
| Painting a Grid With Three Different Colors | Open ↗ |
| Painting the Walls | Open ↗ |
| Pairs of Songs With Total Durations Divisible by 60 | Open ↗ |
| Palindrome Linked List | Open ↗ |
| Palindrome Number | Open ↗ |
| Palindrome Pairs | Open ↗ |
| Palindrome Partitioning | Open ↗ |
| Palindrome Partitioning II | Open ↗ |
| Palindrome Partitioning IV | Open ↗ |
| Palindrome Permutation | Open ↗ |
| Palindrome Removal | Open ↗ |
| Palindromic Substrings | Open ↗ |
| Pancake Sorting | Open ↗ |
| Parallel Courses | Open ↗ |
| Parallel Courses II | Open ↗ |