Improved task 3448

Author: javadev

src/test/kotlin/g3401_3500/s3448_count_substrings_divisible_by_last_digit/SolutionTest.kt

@@ -22,21 +22,64 @@ internal class SolutionTest {
 
     @Test
     fun countSubstrings4() {
-        assertThat<Long>(Solution().countSubstrings("4"), equalTo<Long>(1L))
+        assertThat<Long>(Solution().countSubstrings("28"), equalTo<Long>(2L))
     }
 
     @Test
     fun countSubstrings5() {
-        assertThat<Long>(Solution().countSubstrings("28"), equalTo<Long>(2L))
+        assertThat<Long>(Solution().countSubstrings("04"), equalTo<Long>(2L))
     }
 
     @Test
-    fun countSubstrings6() {
-        assertThat<Long>(Solution().countSubstrings("04"), equalTo<Long>(2L))
+    fun testSingleDigitNumbers() {
+        val solution = Solution()
+        assertThat(solution.countSubstrings("1"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("2"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("3"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("4"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("5"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("6"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("7"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("8"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("9"), equalTo<Long>(1L))
+    }
+
+    @Test
+    fun testDivisibilityBy4() {
+        val solution = Solution()
+        assertThat(solution.countSubstrings("44"), equalTo<Long>(3L))
+        assertThat(solution.countSubstrings("48"), equalTo<Long>(3L))
+        assertThat(solution.countSubstrings("24"), equalTo<Long>(3L))
+    }
+
+    @Test
+    fun testDivisibilityBy8() {
+        val solution = Solution()
+        assertThat(solution.countSubstrings("888"), equalTo<Long>(6L))
+        assertThat(solution.countSubstrings("808"), equalTo<Long>(4L))
+        assertThat(solution.countSubstrings("8888"), equalTo<Long>(10L))
+    }
+
+    @Test
+    fun testDivisibilityBy7() {
+        val solution = Solution()
+        assertThat(solution.countSubstrings("777"), equalTo<Long>(6L))
+        assertThat(solution.countSubstrings("70"), equalTo<Long>(1L))
+    }
+
+    @Test
+    fun testMixedCases() {
+        val solution = Solution()
+        assertThat(solution.countSubstrings("1234"), equalTo<Long>(6L))
+        assertThat(solution.countSubstrings("456"), equalTo<Long>(5L))
+        assertThat(solution.countSubstrings("987"), equalTo<Long>(4L))
     }
 
     @Test
-    fun countSubstrings7() {
-        assertThat<Long>(Solution().countSubstrings("8"), equalTo<Long>(1L))
+    fun testEdgeCases() {
+        val solution = Solution()
+        assertThat(solution.countSubstrings("0"), equalTo<Long>(0L))
+        assertThat(solution.countSubstrings("10"), equalTo<Long>(1L))
+        assertThat(solution.countSubstrings("100"), equalTo<Long>(1L))
     }
 }