@@ -16,7 +16,7 @@ package spltk
 // time complexity: O(n), where n = len(nums)
 // space complexity: O(1)
 func numSubArrayProductLessThanK(nums []int, k int) int {
-if k <= 0 {
+if k <= 1 {
 return 0
 }
 
@@ -42,3 +42,25 @@ func numSubArrayProductLessThanK(nums []int, k int) int {
 }
 return res
 }
+
+// 2019-06-16
+func numSubArrayProductLessThanK2(nums []int, k int) int {
+if k <= 1 {
+return 0
+}
+var (
+prod = 1
+res = 0
+left = 0
+)
+
+for right, val := range nums {
+prod *= val
+for prod >= k {
+prod /= nums[left]
+left++
+}
+res += right - left + 1
+}
+return res
+}

@@ -11,9 +11,16 @@ func TestNumSubArrayProductLessThanK(t *testing.T) {
 
 ks := []int{100, 0, 100}
 expected := []int{8, 0, 4}
-for index, data := range testCases {
-if res := numSubArrayProductLessThanK(data, ks[index]); res != expected[index] {
-t.Errorf("expected %d, got %d", expected[index], res)
+
+functions := []func([]int, int)int{
+numSubArrayProductLessThanK,
+numSubArrayProductLessThanK2,
+}
+for _, func_ := range functions {
+for index, data := range testCases {
+if res := func_(data, ks[index]); res != expected[index] {
+t.Errorf("expected %d, got %d", expected[index], res)
+}
 }
 }
 }