Matrix Patterns

Master Matrix Patterns for DSA + Competitive Programming

Matrix problems involve traversing, transforming, and searching 2D grids.

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Pattern Table

Pattern	Typical Questions	Trigger
Traversal	Row/column/diagonal traversal	Iterate in specific order
Spiral	Spiral order matrix	Clockwise/counter-clockwise
Rotation	Rotate image, transpose	In-place transformation
Simulation	Game of Life, valid sudoku	Cell-by-cell rules
Flood Fill	Paint bucket, island fill	BFS/DFS on grid

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Mental Trigger

2D grid → Traverse in order → Transform → Done.

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Generic Java Matrix Template (Base)

int n = matrix.length, m = matrix[0].length;

for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++)
        // process matrix[i][j]

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Recognition Cheat Sheet

If you see…	Think…
Spiral order output	Four boundaries
Rotate/flip in-place	Transpose + reverse
Cell simulation	Check 8 neighbors
Flood/paint fill	BFS/DFS on grid