Given two sparse matrices 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 |
public class Solution { public int[][] multiply(int[][] A, int[][] B) { int ma = A.length; int na = A[0].length; int mb = B.length;//mb=na int nb = B[0].length; int[][] C = new int[ma][nb]; for(int i=0;i<ma;i++) { for(int j=0;j<na;j++) { if(A[i][j]!=0) { for(int k=0;k<nb;k++) { if(B[j][k]!=0)C[i][k]+=A[i][j]*B[j][k]; } } } } return C; } }