2D Arrays (Matrices)

Key Concepts

• Row-Major: Standard traversal, row by row. Used in most programming languages for memory layout.
• Column-Major: Column by column traversal. Used in languages like Fortran and MATLAB.
• Spiral: Clockwise from outside to inside. Common interview question pattern.
• Diagonal: Traverses along diagonal lines. Useful for matrix operations and pattern recognition.

Java Syntax

// Declare 2D array
int[][] matrix = new int[rows][cols];

// Initialize with values
int[][] matrix = {
  {1, 2, 3},
  {4, 5, 6},
  {7, 8, 9}
};

// Access element
int value = matrix[row][col];

// Row-major traversal
for (int i = 0; i < rows; i++) {
  for (int j = 0; j < cols; j++) {
    System.out.print(matrix[i][j]);
  }
}