Given two Sparse Matrix A and B, return the result of AB.
You may assume that A‘s column number is equal to B‘s row number.
Example1
Input:
[[1,0,0],[-1,0,3]]
[[7,0,0],[0,0,0],[0,0,1]]
Output:
[[7,0,0],[-7,0,3]]
Explanation:
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 |
Example2
Input: [[1,0],[0,1]] [[0,1],[1,0]] Output: [[0,1],[1,0]]
Solution 1:
public class Solution { /** * @param A: a sparse matrix * @param B: a sparse matrix * @return: the result of A * B */ public int[][] multiply(int[][] A, int[][] B) { // write your code here int aRow = A.length; int aCol = A[0].length; int bCol = B[0].length; int[][] res = new int[aRow][bCol]; for (int i = 0; i < aRow; i++) { for (int j = 0; j < aCol; j++) { if (A[i][j] != 0) { for (int k = 0; k < bCol; k++) { res[i][k] += A[i][j] * B[j][k]; } } } } return res; } }
Solution 2:
[LC] 654. Sparse Matrix Multiplication
原文：https://www.cnblogs.com/xuanlu/p/12507368.html