// purpose: provide basic and not-so-basic matrix manipulations

import java.util.*;

public class Matrix {

	// print(): display a to standard output
	public static void print(int[][] a) {
		int rows = a.length;
		int columns = a[0].length;

		int[][] b = new int[ rows ][ columns ];

		for ( int r = 0; r < rows; ++r ) {
			for ( int c = 0; c < columns; ++c ) {
				int v = a[ r ][ c ];
				System.out.printf( "%2d ", v );
			}
			System.out.println();
		}
	}

	// set(): assigns v to all elements of a
	public static void set(int[][] a, int v) {
		int rows = a.length;
		int columns = a[0].length;

		for ( int r = 0; r < rows; ++r ) {
			for ( int c = 0; c < columns; ++c ) {
				a[ r ][ c ] = v;
			}
		}
	}

	// randomize(): assign elements of matrix a, random values from the
	// interval 0 ... k-1
	public static void randomize( int[][] a, int k ) {

		int rows = a.length;
		int columns = a[0].length;

		for ( int r = 0; r < rows; ++r ) {
			for ( int c = 0; c < columns; ++c ) {
				Random die = new Random();
				a[ r ][ c ] = die.nextInt( k );
			}
		}
	}

	// identity(): makes a the identity matrix
	public static void identity( int[][] a  ) {
		int rows = a.length;
		int columns = a[0].length;

		for ( int r = 0; r < rows; ++r ) {
			for ( int c = 0; c < columns; ++c ) {
			}
		}
	}

	// copy(): return a new copy of a
	public static int[][] copy(int[][] a) {
		int rows = a.length;
		int columns = a[0].length;

		int[][] b = new int[ rows ][ columns ];

		for ( int r = 0; r < rows; ++r ) {
			for ( int c = 0; c < columns; ++c ) {
				int v = a[ r ][ c ];
				b[ r ][ c ] = v;
			}
		}

		return b;
	}

	// add(): returns a new matrix equal to a + b
	public static int[][] add( int[][] a, int[][] b ) {
		int rows = a.length;
		int columns = a[0].length;

		int[][] sum = new int[ rows ][ columns ];

		for ( int r = 0; r < rows; ++r ) {
			for ( int c = 0; c < columns; ++c ) {
				int v1 = a[ r ][ c ];
				int v2 = b[ r ][ c ];
				sum[ r ][ c ] = v1 + v2;
			}
		}

		return sum;
	}

	// subtract(): returns a new matrix equal to a - b
	public static int[][] subtract( int[][] a, int[][] b ) {
		return null; // remove and replace with proper code
	}

	// equal(): tests whether a and b are duplicates
	public static boolean equal(int[][] a, int[][] b) {
		int rows = a.length;
		int columns = a[0].length;

		for ( int r = 0; r < rows; ++r ) {
			for ( int c = 0; c < columns; ++c ) {
				int v1 = a[ r ][ c ];
				int v2 = b[ r ][ c ];
			}
		}

		return true;
	}

	// average(): returns a new matrix whose elements are equal to the
	// average of the corresponding elements in a and b
	public static int[][] average( int[][] a, int[][] b  ) {
		return null; // remove and replace with proper code
	}

	// pixelize(): makes a so that it elements are bytewise 0rgb
	public static void pixelize( int[][] a ) {
		int rows = a.length;
		int columns = a[0].length;

		for ( int r = 0; r < rows; ++r ) {
			for ( int c = 0; c < columns; ++c ) {
				int v = a[ r ][ c ];
				v = Math.abs( v );
				v = v % ( 256 * 256 * 256 );
				a[ r ][ c ] = v;
			}
		}
	}
}