4 subtopics · 16 problems
Prefix Sums & Difference Arrays
Range sum queries, range updates, 2D prefix sums, and XOR prefix.
011D Prefix Sums
Answer range sum queries in O(1) after O(n) precomputation.
2 easy3 medium1 hard
| Problem | Difficulty | Link |
|---|---|---|
| 1873D1D Eraser | easy | Solve |
| 1279BVerse For Santa | easy | Solve |
| 1900CAnji's Binary Tree | medium | Solve |
| 1862DIce Cream Balls | medium | Solve |
| 1398CGood Subarrays | medium | Solve |
| 1837EPlayoff Fixing | hard | Solve |
022D Prefix Sums
Extend prefix sums to 2D grids for rectangle sum queries.
1 easy1 medium1 hard
| Problem | Difficulty | Link |
|---|---|---|
| 1873CTarget Practice | easy | Solve |
| 835BThe number on the board | medium | Solve |
| 1203D2Remove the Substring (hard) | hard | Solve |
03Difference Arrays
Apply range increments in O(1) each, then recover the array.
1 easy2 medium1 hard
| Problem | Difficulty | Link |
|---|---|---|
| 1843CSum in Binary Tree | easy | Solve |
| 816BKaren and Coffee | medium | Solve |
| 1904BCollecting Game | medium | Solve |
| 1881EBlock Sequence | hard | Solve |
04XOR Prefix Sums
Use XOR prefix arrays for range XOR queries.
1 easy1 medium1 hard
| Problem | Difficulty | Link |
|---|---|---|
| 1527AAnd Then There Were K | easy | Solve |
| 1554BCobb | medium | Solve |
| 1516BAGAGA XOOORRR | hard | Solve |
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