Add new file TwoSumsTest

TwoSumsTest.java

+import static org.junit.Assert.*;
+import org.junit.Test;
+
+public class TwoSumsTest {
+
+    @Test
+    public void testStudentOneSolution() {
+        int[] nums = { 2, 7, 11, 15 };
+        int target = 18;
+        int[][] expectedPairs = {{2, 16}, {7, 11}};
+        int[][] expectedIndices = {{0, 3}, {1, 2}};
+
+        // Replace StudentOneSolution with the actual name of the class submitted by the first student
+        int[][] actualPairs = StudentOneSolution.findPairs(nums, target);
+        int[][] actualIndices = StudentOneSolution.findIndices(nums, target);
+
+        assertArrayEquals(expectedPairs, actualPairs);
+        assertArrayEquals(expectedIndices, actualIndices);
+    }
+
+    @Test
+    public void testStudentTwoSolution() {
+        int[] nums = { 2, 7, 11, 15 };
+        int target = 18;
+        int[][] expectedPairs = {{2, 16}, {7, 11}};
+        int[][] expectedIndices = {{0, 3}, {1, 2}};
+
+        // Replace StudentTwoSolution with the actual name of the class submitted by the second student
+        int[][] actualPairs = StudentTwoSolution.findPairs(nums, target);
+        int[][] actualIndices = StudentTwoSolution.findIndices(nums, target);
+
+        assertArrayEquals(expectedPairs, actualPairs);
+        assertArrayEquals(expectedIndices, actualIndices);
+    }
+
+    @Test
+    public void testStudentThreeSolution() {
+        int[] nums = { 2, 7, 11, 15 };