Fixed warnings, added unit tests.

Author: javadev

src/main/kotlin/g0001_0100/s0001_two_sum/Solution.kt

@@ -1,6 +1,6 @@
 package g0001_0100.s0001_two_sum
 
-import java.util.*
+import java.util.Arrays
 
 class Solution {
     fun twoSum(nums: IntArray?, target: Int): IntArray {

src/main/kotlin/g0001_0100/s0003_longest_substring_without_repeating_characters/Solution.kt

@@ -9,7 +9,7 @@ class Solution {
         var maxLen = 0
         var curLen = 0
         var start = 0
-        for (i in 0 until s.length) {
+        for (i in s.indices) {
             val cur = s[i]
             if (lastIndices[cur.code] < start) {
                 lastIndices[cur.code] = i

src/test/kotlin/g0001_0100/s0008_string_to_integer_atoi/SolutionTest.kt

@@ -9,4 +9,24 @@ class SolutionTest {
     fun myAtoi() {
         assertThat(Solution().myAtoi("42"), equalTo(42))
     }
+
+    @Test
+    fun myAtoi2() {
+        assertThat(Solution().myAtoi("   -42"), equalTo(-42))
+    }
+
+    @Test
+    fun myAtoi3() {
+        assertThat(Solution().myAtoi("4193 with words"), equalTo(4193))
+    }
+
+    @Test
+    fun myAtoi4() {
+        assertThat(Solution().myAtoi("words and 987"), equalTo(0))
+    }
+
+    @Test
+    fun myAtoi5() {
+        assertThat(Solution().myAtoi("-91283472332"), equalTo(-2147483648))
+    }
 }