Improved task 1.

Author: javadev

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

@@ -1,44 +1,19 @@
 package g0001_0100.s0001_two_sum
 
 // #Easy #Top_100_Liked_Questions #Top_Interview_Questions #Array #Hash_Table
-// #Data_Structure_I_Day_2_Array #2022_03_22_Time_292_ms_(80.69%)_Space_41.6_MB_(60.71%)
-
-import java.util.Arrays
+// #Data_Structure_I_Day_2_Array #Level_1_Day_13_Hashmap #Udemy_Arrays
+// #2022_07_14_Time_234_ms_(92.75%)_Space_37.5_MB_(93.77%)
 
 class Solution {
-    fun twoSum(nums: IntArray?, target: Int): IntArray {
-        if (nums == null || nums.size <= 1) {
-            return IntArray(0)
-        }
-        val result = IntArray(2)
-        var left = 0
-        var right = nums.size - 1
-        val nums1 = Arrays.copyOf(nums, nums.size)
-        Arrays.sort(nums1)
-        while (left < right) {
-            if (nums1[left] + nums1[right] == target) {
-                break
-            } else if (nums1[left] + nums1[right] > target) {
-                right--
-            } else if (nums1[left] + nums1[right] < target) {
-                left++
-            }
-        }
-        for (i in nums.indices) {
-            if (nums1[left] == nums[i]) {
-                result[0] = i
-                break
-            }
-        }
-        for (j in nums.indices.reversed()) {
-            if (nums1[right] == nums[j]) {
-                result[1] = j
-                break
+    fun twoSum(numbers: IntArray, target: Int): IntArray {
+        val indexMap: MutableMap<Int, Int> = HashMap()
+        for (i in numbers.indices) {
+            val requiredNum = target - numbers[i]
+            if (indexMap.containsKey(requiredNum)) {
+                return intArrayOf(indexMap[requiredNum]!!, i)
             }
+            indexMap[numbers[i]] = i
         }
-        val tmp = result[0]
-        result[0] = Math.min(result[0], result[1])
-        result[1] = Math.max(tmp, result[1])
-        return result
+        return intArrayOf(-1, -1)
     }
 }

src/test/kotlin/g0001_0100/s0001_two_sum/SolutionTest.kt

@@ -19,4 +19,9 @@ internal class SolutionTest {
     fun twoSum3() {
         assertThat(Solution().twoSum(intArrayOf(3, 3), 6), equalTo(intArrayOf(0, 1)))
     }
+
+    @Test
+    fun twoSum4() {
+        assertThat(Solution().twoSum(intArrayOf(3, 3), 7), equalTo(intArrayOf(-1, -1)))
+    }
 }