Leetcode 311. Sparse Matrix Multiplication (Medium) (cpp)

Leetcode 311. Sparse Matrix Multiplication (Medium) (cpp)

Tag: Hash Table

Difficulty: Medium

/*311. Sparse Matrix Multiplication (Medium)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 |*/class Solution {public:vector<vector<int>> multiply(vector<vector<int>>& A, vector<vector<int>>& B) {int m = A.size(), n = A[0].size();vector<vector<int>> res(m, vector<int>(B[0].size(), 0));for (int i = 0; i < m; i++) {for (int k = 0; k < n; k++) {if (A[i][k] != 0) {for (int j = 0; j < B[0].size(); j++) {res[i][j] += A[i][k] * B[k][j];}}}}return res;}};