Add Arrays/1570_Dot_Product_of_Two_Sparse_Vectors.java

Author: seanprashad

Arrays/1570_Dot_Product_of_Two_Sparse_Vectors.java

@@ -0,0 +1,32 @@
+class SparseVector {
+    private Map<Integer, Integer> indexMap;
+    
+    public SparseVector(int[] nums) {
+        indexMap = new HashMap<>();
+
+        for (int i = 0; i < nums.length; i++) {
+            if (nums[i] != 0) { indexMap.put(i, nums[i]); }
+        }
+    }
+    
+	// Return the dotProduct of two sparse vectors
+    public int dotProduct(SparseVector vec) {
+        int product = 0;
+        Map<Integer, Integer> vecMap = vec.indexMap;
+
+        for (Map.Entry<Integer, Integer> entry : indexMap.entrySet()) {
+            if (!vecMap.containsKey(entry.getKey())) {
+                continue;
+            }
+
+            product += entry.getValue() * vecMap.get(entry.getKey());
+        }
+        
+        return product;
+    }
+}
+
+// Your SparseVector object will be instantiated and called as such:
+// SparseVector v1 = new SparseVector(nums1);
+// SparseVector v2 = new SparseVector(nums2);
+// int ans = v1.dotProduct(v2);