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Author: cricksmaidiene

MergeSort.java

@@ -0,0 +1,113 @@
+import java.io.*;
+import java.util.*;
+class MergeSort{
+
+	Scanner sc = new Scanner(System.in);
+
+	public static void main(String args[])throws IOException{
+		MergeSort ob = new MergeSort();
+		int n = ob.InputSizeOfArray();
+		if(n==-1) return;
+		int arr[] = new int[n];
+		int flag = ob.InputArrayElements(n,arr);
+		if(flag==-1) return;
+		long sT = System.nanoTime();
+		//ob.DisplayArrayElements(n,arr);
+		ob.MergeSortRoutine(n,arr);
+		//System.out.println("The Sorted Array is:");
+		//ob.DisplayArrayElements(n,arr);
+		long eT = System.nanoTime();
+		float time = eT-sT;
+		System.out.println("Elapsed Time: "+(eT-sT)+"ns "+(eT-sT)/1000+"us "+(eT-sT)/100000+"ms "+(time)/1000000000+"s");
+	}
+
+	public void MergeSortRoutine(int n, int arr[]){
+		int lo = 0;
+		int hi = n-1;
+		if(lo<hi){
+			int mid = (int)(Math.floor((lo+hi)/2));
+			int LArr[] = new int[mid+1];
+			int RArr[] = new int[n-(mid+1)];
+			PopulateArray(LArr,RArr,arr,mid+1);
+			
+			MergeSortRoutine(mid+1,LArr);
+			MergeSortRoutine(n-(mid+1),RArr);
+			
+			Merge(LArr,RArr,arr);
+
+		}
+	}
+
+	public void Merge(int LArr[], int RArr[], int newArr[]){
+		int i=0,j=0,k=0;
+		while(i < LArr.length && j < RArr.length){
+			if(LArr[i]<RArr[j]){
+				newArr[k]=LArr[i];
+				i++;
+			}
+			else{
+				newArr[k]=RArr[j];
+				j++;
+			}
+			k++;
+		}
+		while(i<LArr.length){
+			newArr[k]=LArr[i];
+			i++;
+			k++;
+		}
+		while(j<RArr.length){
+			newArr[k]=RArr[j];
+			j++;
+			k++;
+		}
+	}
+
+	public void PopulateArray(int LArr[], int RArr[], int arr[],int mid){
+		for(int i=0;i<LArr.length;i++)
+			LArr[i]=arr[i];
+		for(int j=mid;j<arr.length;j++)
+			RArr[j-mid]=arr[j];
+	}
+
+	public int InputSizeOfArray(){
+		System.out.print("\nEnter the size of the array: ");
+		int n = sc.nextInt();
+		if(n<=0){
+			System.out.println("No elements in array. Exiting...");
+			return -1;
+		}
+		return n;
+	}
+
+	public int InputArrayElements(int n, int arr[]){
+		 
+		
+		for(int i=0;i<n;i++)
+			arr[i]=(int)(100000*Math.random());
+		return 0;
+		
+		/*
+		System.out.println("Enter "+n+" elements into the array");
+		for(int i=0;i<n;i++){
+			try{
+				arr[i]=sc.nextInt();
+			}	
+			catch(InputMismatchException e)
+			{
+				System.out.println("Result not an integer, exiting...");
+				return -1;
+			}
+		}
+		return 0;
+		*/
+	}
+
+	public void DisplayArrayElements(int n, int arr[]){
+		for(int i=0;i<n;i++)
+			System.out.print(arr[i]+" ");
+		System.out.println();
+	}
+
+
+}