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| 1 | +/** |
| 2 | + * @param {number[][]} a Sparse matrix. |
| 3 | + * @param {number[][]} b Sparse matrix. |
| 4 | + * @return {number[]} Indices of two numbers from 'nums' that add up to 'target' |
| 5 | + * @summary Sparse Matrix Multiplication {@link https://leetcode.com/problems/sparse-matrix-multiplication/} |
| 6 | + * @description Given two sparse matrices, return their multiplication. |
| 7 | + * Space O(n*m) - rows of a and cols of b. |
| 8 | + * Time O(n^3) - with optimization for skipping zeros should skip most of the iteration. |
| 9 | + */ |
| 10 | +const multiply = (a, b) => { |
| 11 | + const rows = a.length; |
| 12 | + const columns = b[0].length; |
| 13 | + |
| 14 | + const c = Array(rows); |
| 15 | + for (let index = 0; index < rows; index++) c[index] = Array(columns).fill(0); |
| 16 | + |
| 17 | + for (let i = 0; i < a.length; i++) { |
| 18 | + for (let j = 0; j < a[i].length; j++) { |
| 19 | + if (a[i][j] === 0) continue; |
| 20 | + |
| 21 | + for (let k = 0; k < b[0].length; k++) { |
| 22 | + if (b[j][k] === 0) continue; |
| 23 | + c[i][k] += a[i][j] * b[j][k]; |
| 24 | + } |
| 25 | + } |
| 26 | + } |
| 27 | + |
| 28 | + return c; |
| 29 | +}; |
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