LeetCode: 566. Reshape the Matrix

LeetCode: 566. Reshape the Matrix

In MATLAB, there is a very useful function called ‘reshape’, which can
reshape a matrix into a new one with different size but keep its
original data.

You’re given a matrix represented by a two-dimensional array, and two
positive integers r and c representing the row number and column
number of the wanted reshaped matrix, respectively.

The reshaped matrix need to be filled with all the elements of the
original matrix in the same row-traversing order as they were.

If the ‘reshape’ operation with given parameters is possible and
legal, output the new reshaped matrix; Otherwise, output the original
matrix.

Example 1: Input: nums = [[1,2], [3,4]] r = 1, c = 4 Output:
[[1,2,3,4]] Explanation: The row-traversing of nums is [1,2,3,4]. The
new reshaped matrix is a 1 * 4 matrix, fill it row by row by using the
previous list. Example 2: Input: nums = [[1,2], [3,4]] r = 2, c = 4
Output: [[1,2], [3,4]] Explanation: There is no way to reshape a 2 *
2 matrix to a 2 * 4 matrix. So output the original matrix. Note: The
height and width of the given matrix is in range [1, 100]. The given r
and c are all positive.

public class Solution {    public int[][] matrixReshape(int[][] nums, int r, int c) {        int r1 = nums.length;        int c1 = nums[0].length;        if (r1 * c1 != r * c) {            return nums;        }        int [] temp = new int[r1 * c1];        for (int i = 0; i < r1; i++) {            for (int j = 0; j < c1; j++) {                temp[c1 * i + j] = nums[i][j];            }        }        int[][] result = new int[r][c];        for (int i = 0; i < r; i++) {            for (int j = 0; j < c; j++) {                result[i][j] = temp[i * c + j];            }        }        return result;    }}