BAEL-3399: How to merge two sorted arrays into a sorted array

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/sortedarrays/SortedArrays.java

@@ -0,0 +1,34 @@
+package com.baeldung.algorithms.sortedarrays;
+
+public class SortedArrays {
+
+    public static int[] merge(int[] first, int[] second) {
+
+        int m = first.length;
+        int n = second.length;
+
+        int i, j, k;
+        i = j = k = 0;
+
+        int[] result = new int[m + n];
+
+        while (i < m && j < n) {
+
+            if (first[i] < second[j]) {
+                result[k++] = first[i++];
+            } else {
+                result[k++] = second[j++];
+            }
+        }
+
+        while (i < m) {
+            result[k++] = first[i++];
+        }
+
+        while (j < n) {
+            result[k++] = second[j++];
+        }
+
+        return result;
+    }
+}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/sortedarrays/SortedArraysUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.algorithms.sortedarrays;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import org.junit.jupiter.api.Test;
+
+public class SortedArraysUnitTest {
+
+    @Test
+    public void givenTwoSortedArraysWhenMergeThenReturnMergedSortedArray() {
+
+        int[] first = { 3, 7 };
+        int[] second = { 4, 8, 11 };
+        int[] result = { 3, 4, 7, 8, 11 };
+
+        assertArrayEquals(result, SortedArrays.merge(first, second));
+    }
+
+    @Test
+    public void givenTwoSortedArraysWithDuplicatesWhenMergeThenReturnMergedSortedArray() {
+
+        int[] first = { 3, 3, 7 };
+        int[] second = { 4, 8, 8, 11 };
+        int[] result = { 3, 3, 4, 7, 8, 8, 11 };
+
+        assertArrayEquals(result, SortedArrays.merge(first, second));
+    }
+}