Practice problems across 75+ categories
Practice problems frequently asked at Counting • 166 problems | 58 Easy | 87 Medium | 20 Hard
| # | Problem | Difficulty | Topics |
|---|---|---|---|
| 121 | Number of Equal Count Substrings | Medium | Hash TableStringSliding Window |
| 122 | Number of Equivalent Domino Pairs | Easy | ArrayHash TableCounting |
| 123 | Number of Good Pairs | Easy | ArrayHash TableMath |
| 124 | Number of Nodes in the Sub-Tree With the Same Label | Medium | Hash TableTreeDepth-First Search |
| 125 | Number of Pairs of Interchangeable Rectangles | Medium | ArrayHash TableMath |
| 126 | Number of Pairs of Strings With Concatenation Equal to Target | Medium | ArrayHash TableString |
| 127 | Number of Same-End Substrings | Medium | ArrayHash TableString |
| 128 | Number of Unique Categories | Medium | Union FindInteractiveCounting |
| 129 | Pairs of Songs With Total Durations Divisible by 60 | Medium | ArrayHash TableCounting |
| 130 | Rank Teams by Votes | Medium | ArrayHash TableString |
| 131 | Ransom Note | Easy | Hash TableStringCounting |
| 132 | Rearrange Characters to Make Target String | Easy | Hash TableStringCounting |
| 133 | Rearrange String k Distance Apart | Hard | Hash TableStringGreedy |
| 134 | Redistribute Characters to Make All Strings Equal | Easy | Hash TableStringCounting |
| 135 | Remove Letter To Equalize Frequency | Easy | Hash TableStringCounting |
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