import java.util.Scanner;

public class TwoPointerBinarySort {

//METHOD TO PRINT ARRAY

static void displayArray(int a[]){

for(int i=0; i<a.length; i++){

System.out.print(a[i] + " ");

}

}

//METHOD TO SWAP THE ELEMENTS OF ARRAY

static void swapElements(int a[], int i, int j){

int temp= a[i];

a[i]= a[j];

a[j]= temp;

}

//METHOD TO SORT ZERO AND ONE USING TWO-POINTER VARIABLES

static void sortBinary(int a[]){

int left=0, right=a.length-1;

while(left<right){

if(a[left]==0){

left++;

}

else if(a[right]==1){

right--;

}

else{

swapElements(a, left, right);

left++;

right--;

}

}

System.out.print("Sorted zero-one array: ");

displayArray(a);

}

public static void main(String[] args) {

Scanner sc= new Scanner(System.in);

//ARRAY SIZE AND ELEMENTS INPUT

System.out.print("Enter size of array: ");

int size= sc.nextInt();

int arr[]= new int[size];

System.out.print("Enter " + size + " binary numbers: ");

for(int i=0; i<size; i++){

arr[i]= sc.nextInt();

}

sortBinary(arr);

}

}