Create AdaptiveMergeSort.java

Author: anant-jain01

src/main/java/com/thealgorithms/sorts/AdaptiveMergeSort.java

@@ -0,0 +1,57 @@
+package com.thealgorithms.sorts;
+
+import java.util.Arrays;
+
+/**
+ * @author Anant Jain (https://github.com/anant-jain01)
+ * @see https://en.wikipedia.org/wiki/Merge_sort
+ */
+public class AdaptiveMergeSort implements SortAlgorithm {
+
+    @Override
+    public <T extends Comparable<T>> T[] sort(T[] array) {
+        if (array == null || array.length < 2) {
+            return array;
+        }
+
+        T[] aux = array.clone();
+        adaptiveMergeSort(array, aux, 0, array.length - 1);
+        return array;
+    }
+
+    private <T extends Comparable<T>> void adaptiveMergeSort(T[] array, T[] aux, int low, int high) {
+        if (high <= low) return;
+
+        int mid = low + (high - low) / 2;
+
+        adaptiveMergeSort(aux, array, low, mid);
+        adaptiveMergeSort(aux, array, mid + 1, high);
+
+        if (array[mid].compareTo(array[mid + 1]) <= 0) {
+            System.arraycopy(array, low, aux, low, high - low + 1);
+            return;
+        }
+
+        merge(array, aux, low, mid, high);
+    }
+
+    private <T extends Comparable<T>> void merge(T[] array, T[] aux, int low, int mid, int high) {
+        int i = low, j = mid + 1;
+
+        for (int k = low; k <= high; k++) {
+            if (i > mid) aux[k] = array[j++];
+            else if (j > high) aux[k] = array[i++];
+            else if (array[j].compareTo(array[i]) < 0) aux[k] = array[j++];
+            else aux[k] = array[i++];
+        }
+    }
+
+    public static void main(String[] args) {
+        Integer[] integers = {12, 11, 13, 5, 6, 7};
+        AdaptiveMergeSort mergeSort = new AdaptiveMergeSort();
+        System.out.println(Arrays.toString(mergeSort.sort(integers)));
+
+        String[] strings = {"zebra", "apple", "mango", "banana"};
+        System.out.println(Arrays.toString(mergeSort.sort(strings)));
+    }
+}