Algorithm Solutions: Grid Patterns, Matrix Transformations, and Pairing Problems
Tile Pattern
Problem: We have a 10^9×10^9 grid where each cell's color is determined by (i%n, j%n). We're given an n×n character matrix and need to answer q queries about the number of black cells in specified rectangular regions.
Solution: We use a 2D prefix sum approach to efficiently count black cells in any rectangle.
#include <iostream ...
Posted on Mon, 17 Aug 2026 16:54:20 +0000 by DrJonesAC2