Given two  A and B, return the result of AB.

You may assume that A's column number is equal to B's row number.

Example:

A = [  [ 1, 0, 0],  [-1, 0, 3]]B = [  [ 7, 0, 0 ],  [ 0, 0, 0 ],  [ 0, 0, 1 ]]     |  1 0 0 |   | 7 0 0 |   |  7 0 0 |AB = | -1 0 3 | x | 0 0 0 | = | -7 0 3 |                  | 0 0 1 |

1 public class Solution { 2     public int[][] multiply(int[][] A, int[][] B) { 3         int mA = A.length, nA = A[0].length, nB = B[0].length; 4         int[][] result = new int[mA][nB]; 5          6         for (int i = 0; i < mA; i++) { 7             for (int j = 0; j < nA; j++) { 8                 if (A[i][j] != 0) { 9                     for (int k = 0; k < nB; k++) {10                         if (B[j][k] != 0)11                             result[i][k] += A[i][j] * B[j][k];12                     }13                 }14             }15         }16         return result;17     }18 }