cpp: add «713. Subarray Product Less Than K»

Signed-off-by: Matej Focko <me@mfocko.xyz>

cpp/subarray-product-less-than-k.cpp

@@ -0,0 +1,43 @@
+#include <vector>
+
+class Solution {
+  public:
+    int numSubarrayProductLessThanK(const std::vector<int> &nums, int k) {
+        if (k <= 1) {
+            return 0;
+        }
+
+        int count = 0;
+        int product = 1;
+        for (std::size_t i = 0, j = 0; j < nums.size(); ++j) {
+            product *= nums[j];
+
+            for (; product >= k; ++i) {
+                product /= nums[i];
+            }
+
+            count += j - i + 1;
+        }
+
+        return count;
+    }
+};
+
+#ifdef _MF_TEST
+#include <gtest/gtest.h>
+
+TEST(examples, _1) {
+    Solution s;
+    EXPECT_EQ(s.numSubarrayProductLessThanK(std::vector{10, 5, 2, 6}, 100), 8);
+}
+
+TEST(examples, _2) {
+    Solution s;
+    EXPECT_EQ(s.numSubarrayProductLessThanK(std::vector{1, 2, 3}, 0), 0);
+}
+
+int main(int argc, char **argv) {
+    testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
+#endif