Created Java Merge Sort Implementation

Author: aqche

Sorting/MergeSort.java

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+public class MergeSort {
+    
+    public static void mergeSort(int[] arr) {
+        mergeSort(arr, 0, arr.length-1);
+    }
+
+    public static void mergeSort(int[] arr, int leftIndex, int rightIndex) {
+        int arrLen = rightIndex + 1 - leftIndex;
+
+        if (arrLen > 1) {
+            int midIndex = (leftIndex + rightIndex) / 2;
+
+            mergeSort(arr, leftIndex, midIndex);
+            mergeSort(arr, midIndex+1, rightIndex);
+            merge(arr, leftIndex, midIndex, rightIndex);
+        }
+    }
+
+    public static void merge(int[] arr, int leftIndex, int midIndex, int rightIndex) {
+        int leftLen = midIndex + 1 - leftIndex;
+        int rightLen = rightIndex - midIndex;
+
+        int[] leftArr = new int[leftLen];
+        int[] rightArr = new int[rightLen];
+
+        for (int i = 0; i < leftLen; i++) {
+            leftArr[i] = arr[i+leftIndex];
+        }
+
+        for (int j = 0; j < rightLen; j++) {
+            rightArr[j] = arr[j+midIndex+1];
+        }
+
+        int i = 0;
+        int j = 0;
+        int k = leftIndex;
+
+        while (i < leftLen && j < rightLen) {
+            if (leftArr[i] < rightArr[j]) {
+                arr[k] = leftArr[i];
+                i++;
+            } else {
+                arr[k] = rightArr[j];
+                j++;
+            }
+            k++;
+        }
+
+        while (i < leftLen) {
+            arr[k] = leftArr[i];
+            i++;
+            k++;            
+        }
+
+        while (j < rightLen) {
+            arr[k] = rightArr[j];
+            j++;
+            k++;            
+        }
+    }
+}