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:
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| 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 |
|
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| public class Solution {
public int[][] multiply(int[][] A, int[][] B) {
if (A == null || A.length == 0 || B == null || B.length == 0 || A[0].length != B.length) {
return new int[0][0];
}
int[][] result = new int[A.length][B[0].length];
int length = B[0].length;
for (int i = 0; i < A.length; i++) {
for (int j = 0; j < A[0].length; j++) {
if (A[i][j] == 0) continue;
for (int k = 0; k < length; k++) {
result[i][k] += A[i][j] * B[j][k];
}
}
}
return result;
}
}
|