# 311. Sparse Matrix Multiplication

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 |

## Solution <a href="#solution" id="solution"></a>

```java
public class Solution {
      public int[][] multiply(int[][] A, int[][] B) {
        int row1 = A.length;
        int col1 = A[0].length;
        int row2 = B.length;
        int col2 = B[0].length;

        int[][] result = new int[row1][col2];
        for (int i = 0; i < row1; i++) {
            for (int j = 0; j < col1; j++) {
                if (A[i][j] != 0) {

                    for (int k = 0; k < col2; k++) {
                        if (B[j][k] != 0) {
                            result[i][k] += A[i][j] * B[j][k];
                        }
                    }

                }
            }
        }

        return result;
    }
}
```


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