Add tests for TwoSumProblem and reduce duplication (fixes #4177) (#4176)

src/main/java/com/thealgorithms/misc/TwoSumProblem.java

@@ -1,109 +0,0 @@
-package com.thealgorithms.misc;
-
-import java.util.*;
-import java.util.stream.Collectors;
-
-public class TwoSumProblem {
-
-    public static void main(String[] args) {
-        Scanner scan = new Scanner(System.in);
-        System.out.print("Enter the target sum ");
-        int ts = scan.nextInt();
-        System.out.print("Enter the number of elements in the array ");
-        int n = scan.nextInt();
-        System.out.println("Enter all your array elements:");
-        int[] arr = new int[n];
-        for (int i = 0; i < n; i++) {
-            arr[i] = scan.nextInt();
-        }
-        TwoSumProblem t = new TwoSumProblem();
-        System.out.println(
-            "Brute Force Approach\n" +
-            Arrays.toString(t.BruteForce(arr, ts)) +
-            "\n"
-        );
-        System.out.println(
-            "Two Pointer Approach\n" +
-            Arrays.toString(t.TwoPointer(arr, ts)) +
-            "\n"
-        );
-        System.out.println(
-            "Hashmap Approach\n" + Arrays.toString(t.HashMap(arr, ts))
-        );
-    }
-
-    public int[] BruteForce(int[] nums, int target) {
-        //Brute Force Approach
-        int[] ans = new int[2];
-        for (int i = 0; i < nums.length; i++) {
-            for (int j = i + 1; j < nums.length; j++) {
-                if (nums[i] + nums[j] == target) {
-                    ans[0] = i;
-                    ans[1] = j;
-
-                    break;
-                }
-            }
-        }
-
-        return ans;
-    }
-
-    public int[] TwoPointer(int[] nums, int target) {
-        // HashMap Approach
-        int[] ans = new int[2];
-        HashMap<Integer, Integer> hm = new HashMap<Integer, Integer>();
-        for (int i = 0; i < nums.length; i++) {
-            hm.put(i, nums[i]);
-        }
-        HashMap<Integer, Integer> temp = hm
-            .entrySet()
-            .stream()
-            .sorted((i1, i2) -> i1.getValue().compareTo(i2.getValue()))
-            .collect(
-                Collectors.toMap(
-                    Map.Entry::getKey,
-                    Map.Entry::getValue,
-                    (e1, e2) -> e1,
-                    LinkedHashMap::new
-                )
-            );
-
-        int start = 0;
-        int end = nums.length - 1;
-        while (start < end) {
-            int currSum = (Integer) temp.values().toArray()[start] +
-            (Integer) temp.values().toArray()[end];
-
-            if (currSum == target) {
-                ans[0] = (Integer) temp.keySet().toArray()[start];
-                ans[1] = (Integer) temp.keySet().toArray()[end];
-                break;
-            } else if (currSum > target) {
-                end -= 1;
-            } else if (currSum < target) {
-                start += 1;
-            }
-        }
-        return ans;
-    }
-
-    public int[] HashMap(int[] nums, int target) {
-        //Using Hashmaps
-        int[] ans = new int[2];
-        HashMap<Integer, Integer> hm = new HashMap<Integer, Integer>();
-        for (int i = 0; i < nums.length; i++) {
-            hm.put(nums[i], i);
-        }
-        for (int i = 0; i < nums.length; i++) {
-            int t = target - nums[i];
-            if (hm.containsKey(t) && hm.get(t) != i) {
-                ans[0] = i;
-                ans[1] = hm.get(t);
-                break;
-            }
-        }
-
-        return ans;
-    }
-}

src/main/java/com/thealgorithms/others/TwoPointers.java

@@ -11,21 +11,6 @@ import java.util.Arrays;
  */
 class TwoPointers {
 
-    public static void main(String[] args) {
-        int[] arr = { 10, 20, 35, 50, 75, 80 };
-        int key = 70;
-        assert isPairedSum(arr, key);
-        /* 20 + 60 == 70 */
-
-        arr = new int[] { 1, 2, 3, 4, 5, 6, 7 };
-        key = 13;
-        assert isPairedSum(arr, key);
-        /* 6 + 7 == 13 */
-
-        key = 14;
-        assert !isPairedSum(arr, key);
-    }
-
     /**
      * Given a sorted array arr (sorted in ascending order). Find if there
      * exists any pair of elements such that their sum is equal to key.
@@ -35,7 +20,7 @@ class TwoPointers {
      * @return {@code true} if there exists a pair of elements, {@code false}
      * otherwise.
      */
-    private static boolean isPairedSum(int[] arr, int key) {
+    public static boolean isPairedSum(int[] arr, int key) {
         /* array sorting is necessary for this algorithm to function correctly */
         Arrays.sort(arr);
         int i = 0;

src/test/java/com/thealgorithms/others/TwoPointersTest.java

@@ -0,0 +1,44 @@
+package com.thealgorithms.others;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+
+public class TwoPointersTest {
+
+
+    @Test
+    void twoPointersFirstTestCase(){
+        int[] arr = {2,6,9,22,121};
+        int key = 28;
+        assertEquals(true, TwoPointers.isPairedSum(arr,key));
+    }
+
+    @Test
+    void twoPointersSecondTestCase(){
+        int[] arr = {-1,-12,12,0,8};
+        int key = 0;
+        assertEquals(true, TwoPointers.isPairedSum(arr,key));
+    }
+
+    @Test
+    void twoPointersThirdTestCase(){
+        int[] arr = {12,35,12,152,0};
+        int key = 13;
+        assertEquals(false, TwoPointers.isPairedSum(arr,key));
+    }
+
+    @Test
+    void twoPointersFourthTestCase(){
+        int[] arr = {-2,5,-1,52,31};
+        int key = -3;
+        assertEquals(true, TwoPointers.isPairedSum(arr,key));
+    }
+
+    @Test
+    void twoPointersFiftiethTestCase(){
+        int[] arr = {25,1,0,61,21};
+        int key = 12;
+        assertEquals(false, TwoPointers.isPairedSum(arr,key));
+    }
+}