Sparse Matrix Multiplication

Author: charlesbuczel

0311_sparseMatrixMultiplication.js

@@ -0,0 +1,29 @@
+/**
+ * @param {number[][]} a Sparse matrix.
+ * @param {number[][]} b Sparse matrix.
+ * @return {number[]} Indices of two numbers from 'nums' that add up to 'target'
+ * @summary Sparse Matrix Multiplication {@link https://leetcode.com/problems/sparse-matrix-multiplication/}
+ * @description Given two sparse matrices, return their multiplication.
+ * Space O(n*m) - rows of a and cols of b.
+ * Time O(n^3) - with optimization for skipping zeros should skip most of the iteration.
+ */
+const multiply = (a, b) => {
+  const rows = a.length;
+  const columns = b[0].length;
+
+  const c = Array(rows);
+  for (let index = 0; index < rows; index++) c[index] = Array(columns).fill(0);
+
+  for (let i = 0; i < a.length; i++) {
+    for (let j = 0; j < a[i].length; j++) {
+      if (a[i][j] === 0) continue;
+
+      for (let k = 0; k < b[0].length; k++) {
+        if (b[j][k] === 0) continue;
+        c[i][k] += a[i][j] * b[j][k];
+      }
+    }
+  }
+
+  return c;
+};