Initial commit

Implementations.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

src/MergeSort.java

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+/**
+ * Created by Mohammad Haider (haidmoham) on 7/19/16.
+ */
+import java.util.*;
+
+public class MergeSort {
+    public static void main(String[] args) {
+        Integer[] a = {2, 6, 3, 5, 1};
+
+        mergeSort(a);
+
+        System.out.println(Arrays.toString(a));
+    }
+    public static Comparable[] mergeSort(Comparable[] list){
+        if (list.length <= 1){
+            return list;
+        }
+
+        Comparable[] first = new Comparable[list.length / 2];
+        Comparable[] second = new Comparable[list.length - first.length];
+        System.arraycopy(list, 0, first, 0, first.length);
+        System.arraycopy(list, first.length, second, 0, second.length);
+
+        mergeSort(first);
+        mergeSort(second);
+
+        merge(first, second, list);
+        return list;
+    }
+    private static void merge(Comparable[] first, Comparable[] second, Comparable[] result){
+        int iFirst = 0;
+        int iSecond = 0;
+        int iMerged = 0;
+
+        while (iFirst < first.length && iSecond < second.length){
+            if(first[iFirst].compareTo(second[iSecond]) < 0) {
+                result[iMerged] = first[iFirst];
+                iFirst++;
+            }
+            else {
+                result[iMerged] = second[iSecond];
+                iSecond++;
+            }
+            iMerged++;
+        }
+        System.arraycopy(first, iFirst, result, iMerged, first.length - iFirst);
+        System.arraycopy(second, iSecond, result, iMerged, second.length - iSecond);
+    }
+}