How to swap rows and columns of a 2d array?

Question

I\'m trying to write a method for \'transpose\' a two-dimensional array of integers, in which the rows and columns of the original matrix are exchanged.

However, I have n

Answer 1

You could iterate over the rows and columns and assign each element [i,j] to the transposed [j,i]:

/**
 * Transposses a matrix.
 * Assumption: mat is a non-empty matrix. i.e.:
 * 1. mat != null
 * 2. mat.length > 0
 * 3. For every i, mat[i].length are equal and mat[i].length > 0
 */
public static int[][] transpose(int[][] mat) {
    int[][] result = new int[mat[0].length][mat.length];
    for (int i = 0; i < mat.length; ++i) {
        for (int j = 0; j < mat[0].length; ++j) {
            result[j][i] = mat[i][j];
        }
    }
    return result;
}