Added merge sort program

Author: Saurav-Sutaria

MergeSort.java

@@ -0,0 +1,50 @@
+import java.util.Scanner;
+
+public class MergeSort{
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        int[] arr = new int[n];
+        for(int i=0;i<n;i++) arr[i] = sc.nextInt();
+        mergeSort(arr,0,n-1);
+        for(int i:arr) System.out.print(i + ",");
+        System.out.println();  
+    }
+    public static void mergeSort(int[] arr,int l,int r){
+        if(l < r){
+            int m = (l+r)/2;
+            mergeSort(arr, l, m);
+            mergeSort(arr, m+1, r);
+            merge(arr,l,m,r);
+        }
+    }
+    public static void merge(int[] arr,int l,int m,int r){
+        int n1 = m - l + 1;
+        int n2 = r -m;
+        int[] left = new int[n1];
+        int[] right = new int[n2];
+
+        for(int i=0;i<n1;i++) left[i] = arr[l + i];
+        for(int i=0;i<n2;i++) right[i] = arr[m + i + 1];
+
+        int i = 0, j= 0,k = l;
+        while(i< n1 && j < n2){
+            if(left[i] < right[j]){
+                arr[k] = left[i];
+                i++;k++;
+            }
+            else{
+                arr[k] = right[j];
+                j++;k++;
+            }
+        }
+        while(i < n1){
+            arr[k] = left[i];
+            i++;k++;
+        }
+        while(j < n2){
+            arr[k] = right[j];
+            j++;k++;
+        }
+    }
+}