Make given Binary array of size two to all 0s in a single line

Given a binary array arr[N], (where N = 2) of size two having at least one element as zero. The task is to write a single line function to set both elements of the array to zero. There is a constraint to writing the function. The ternary operator and direct assignment of elements cannot be used.

As per problem constraints, only three combinations of array elements are possible:

1. arr[0] = 1 and arr[1] = 0
2. arr[0] = 0 and arr[1] = 1
3. arr[0] = 0 and arr[1] = 0

This article discusses the following methods:

1. Using only assignment operator.
2. Using assignment operator two times.
3. negation (!) operator (logical NOT).

Let's start discussing each of these methods in detail.

1. Using only assignment operator:

The assignment operator can be used to set both the elements of the given binary array to 0, but in this approach, the indexes are not used directly. 

Approach:

There are three ways to achieve this:

1. arr[arr[1]] = arr[arr[0]]
If arr={0, 1}, then arr[0] will be assigned to arr[1].
If arr={1, 0}, then arr[1] will be assigned to arr[0].

2. arr[arr[1]] = 0
If arr[1]=0, then arr[0] will be 1, so arr[arr[1]] will make arr[0]=0.
If arr[1]=1, then arr[1] will be 1, so arr[arr[1]] will make arr[1]=0.

3. arr[1 – arr[0]] = arr[1 – arr[1]]
If arr[1]=0 and arr[0]=1, then 1-arr[1] will be 1, so arr[1] will be assigned to arr[0].
If arr[1]=1 and arr[0]=0, then 1-arr[1] will be 0, so arr[0] will be assigned to arr[1].

Below is the C++ code to implement the approach:

// C++ program to set both elements
// to 0 in binary array[2].
#include <iostream>
using namespace std;

void MakeBothZeros(int arr[])
{
    arr[arr[1]] = arr[arr[0]];

    // Two other approaches to solve 
    // the problem
    // arr[arr[1]] = 0;
    // arr[1 - arr[0]] = arr[1 - arr[1]];
}

// Driver code
int main()
{
    int First_Arr[] = {0, 1};
    MakeBothZeros(First_Arr);
    cout << First_Arr[0] << " " << 
            First_Arr[1] << endl;

    int Second_Arr[] = {1, 0};
    MakeBothZeros(Second_Arr);
    cout << Second_Arr[0] << " " << 
            Second_Arr[1] << endl;

    int Thrd_Arr[] = {0, 0};
    MakeBothZeros(Thrd_Arr);
    cout << Thrd_Arr[0] << " " << 
            Thrd_Arr[1] << endl;

    return 0;
}

// Java program to set both elements
// to 0 in binary array[2]
import java.util.*;
class GFG{

static void MakeBothZeros(int arr[])
{
    arr[arr[1]] = arr[arr[0]];

    // Two other approaches to solve 
    // the problem
    // arr[arr[1]] = 0;
    // arr[1 - arr[0]] = arr[1 - arr[1]];
}

// Driver code
public static void main(String[] args)
{
    int First_Arr[] = {0, 1};
    MakeBothZeros(First_Arr);
    System.out.print(First_Arr[0]+ " " +  
            First_Arr[1] +"\n");

    int Second_Arr[] = {1, 0};
    MakeBothZeros(Second_Arr);
    System.out.print(Second_Arr[0]+ " " +  
            Second_Arr[1] +"\n");

    int Thrd_Arr[] = {0, 0};
    MakeBothZeros(Thrd_Arr);
    System.out.print(Thrd_Arr[0]+ " " +  
            Thrd_Arr[1] +"\n");

}
}

// This code is contributed by 29AjayKumar 

# Python code for the above approach
def MakeBothZeros(arr):
    arr[arr[1]] = arr[arr[0]]

    # Two other approaches to solve
    # the problem
    # arr[arr[1]] = 0;
    # arr[1 - arr[0]] = arr[1 - arr[1]];

# Driver code
First_Arr = [0, 1]
MakeBothZeros(First_Arr)
print(f"{First_Arr[0]} {First_Arr[1]}  ")

Second_Arr = [1, 0]
MakeBothZeros(Second_Arr)
print(f"{Second_Arr[0]} {Second_Arr[1]} ")

Thrd_Arr = [0, 0]
MakeBothZeros(Thrd_Arr)
print(f"{Thrd_Arr[0]} {Thrd_Arr[1]} ")

# This code is contributed by GFGKING

// C# program to set both elements
// to 0 in binary array[2]
using System;
class GFG {

  static void MakeBothZeros(int[] arr)
  {
    arr[arr[1]] = arr[arr[0]];

    // Two other approaches to solve
    // the problem
    // arr[arr[1]] = 0;
    // arr[1 - arr[0]] = arr[1 - arr[1]];
  }

  // Driver code
  public static void Main()
  {
    int[] First_Arr = { 0, 1 };
    MakeBothZeros(First_Arr);
    Console.WriteLine(First_Arr[0] + " "
                      + First_Arr[1]);

    int[] Second_Arr = { 1, 0 };
    MakeBothZeros(Second_Arr);
    Console.WriteLine(Second_Arr[0] + " "
                      + Second_Arr[1]);

    int[] Thrd_Arr = { 0, 0 };
    MakeBothZeros(Thrd_Arr);
    Console.WriteLine(Thrd_Arr[0] + " " + Thrd_Arr[1]);
  }
}

// This code is contributed by ukasp.

  <script>
        // JavaScript code for the above approach

        function MakeBothZeros(arr) {
            arr[arr[1]] = arr[arr[0]];

            // Two other approaches to solve 
            // the problem
            // arr[arr[1]] = 0;
            // arr[1 - arr[0]] = arr[1 - arr[1]];
        }

        // Driver code

        let First_Arr = [0, 1];
        MakeBothZeros(First_Arr);
        document.write(First_Arr[0] + " " +
            First_Arr[1] + "<br>");

        let Second_Arr = [1, 0];
        MakeBothZeros(Second_Arr);
        document.write(Second_Arr[0] + " " +
            Second_Arr[1] + '<br>');

        let Thrd_Arr = [0, 0];
        MakeBothZeros(Thrd_Arr);
        document.write(Thrd_Arr[0] + " " +
            Thrd_Arr[1] + '<br>');

  // This code is contributed by Potta Lokesh
    </script>

0 0
0 0
0 0

Time Complexity: O(1), the code will run in a constant time.
Auxiliary Space: O(1), no extra space is required, so it is a constant.

2. Using assignment operator two times:

As listed under the constraints, direct assignment is not allowed. Thus arr[0]=0 and arr[1]=0 are not valid statements. The assignment operator will be used twice to set both elements to zero.

Approach:

There are three ways to achieve this:

1. arr[0] = arr[1] = arr[0] & arr[1]
if any one of the elements is 1. 
AND of 1 and 0 is always 0. So, both gets value 0.

2. arr[0] = arr[1] -= arr[1]
If arr[1]=1 then arr[1] gets 1-1=0 so, both becomes 0.

3. arr[1] = arr[0] -= arr[0]
If arr[0]=1, then arr[0] gets 1-1=0.
else arr[0]= 0-0 = 0. So, both becomes 0.

Below is the C++ program to implement the approach:

// C++ program to set both elements
// to 0 in binary array[2].
#include <iostream>
using namespace std;

void MakeBothZeros(int arr[])
{
    arr[0] = arr[1] = arr[0] & arr[1];

    // Two other approaches to solve 
    // the problem
    // arr[0] = arr[1] -= arr[1];
    // arr[1] = arr[0] -= arr[0];
}

// Driver code
int main()
{
    int First_Arr[] = {0, 1};
    MakeBothZeros(First_Arr);
    cout << First_Arr[0] << " " << 
            First_Arr[1] << endl;

    int Second_Arr[] = {1, 0};
    MakeBothZeros(Second_Arr);
    cout << Second_Arr[0] << " " << 
            Second_Arr[1] << endl;

    int Thrd_Arr[] = {0, 0};
    MakeBothZeros(Thrd_Arr);
    cout << Thrd_Arr[0] << " " << 
            Thrd_Arr[1] << endl;

    return 0;
}

// Java program to set both elements
// to 0 in binary array[2].

import java.util.*;

class GFG{

static void MakeBothZeros(int arr[])
{
    arr[0] = arr[1] = arr[0] & arr[1];

    // Two other approaches to solve 
    // the problem
    // arr[0] = arr[1] -= arr[1];
    // arr[1] = arr[0] -= arr[0];
}

// Driver code
public static void main(String[] args)
{
    int First_Arr[] = {0, 1};
    MakeBothZeros(First_Arr);
    System.out.print(First_Arr[0]+ " " +  
            First_Arr[1] +"\n");

    int Second_Arr[] = {1, 0};
    MakeBothZeros(Second_Arr);
    System.out.print(Second_Arr[0]+ " " +  
            Second_Arr[1] +"\n");

    int Thrd_Arr[] = {0, 0};
    MakeBothZeros(Thrd_Arr);
    System.out.print(Thrd_Arr[0]+ " " +  
            Thrd_Arr[1] +"\n");

}
}

// This code is contributed by 29AjayKumar

# Python program to set both elements
# to 0 in binary array[2].
def MakeBothZeros(arr):

    arr[0] = arr[1] = arr[0] & arr[1]

    # Two other approaches to solve
    # the problem
    # arr[0] = arr[1] -= arr[1];
    # arr[1] = arr[0] -= arr[0];

# Driver code
First_Arr = [0, 1]
MakeBothZeros(First_Arr)
print(First_Arr[0], end=" ")
print(First_Arr[1])

Second_Arr = [0, 1]
MakeBothZeros(Second_Arr)
print(Second_Arr[0], end=" ")
print(Second_Arr[1])


Thrd_Arr = [0, 0]
MakeBothZeros(Thrd_Arr)
print(Thrd_Arr[0], end=" ")
print(Thrd_Arr[1])

# This code is contributed by Samim Hossain Mondal.

// C# program to set both elements
// to 0 in binary array[2].
using System;
public class GFG
{

  static void MakeBothZeros(int []arr) 
  {
    arr[0] = arr[1] = arr[0] & arr[1];

    // Two other approaches to solve
    // the problem
    // arr[0] = arr[1] -= arr[1];
    // arr[1] = arr[0] -= arr[0];
  }

  // Driver code
  public static void Main(String[] args) {
    int[] First_Arr = { 0, 1 };
    MakeBothZeros(First_Arr);
    Console.Write(First_Arr[0] + " " + First_Arr[1] + "\n");

    int []Second_Arr = { 1, 0 };
    MakeBothZeros(Second_Arr);
    Console.Write(Second_Arr[0] + " " + Second_Arr[1] + "\n");

    int []Thrd_Arr = { 0, 0 };
    MakeBothZeros(Thrd_Arr);
    Console.Write(Thrd_Arr[0] + " " + Thrd_Arr[1] + "\n");

  }
}

// This code is contributed by Rajput-Ji

<script>
// Javascript program to set both elements
// to 0 in binary array[2].

function MakeBothZeros(arr) {

    arr[0] = arr[1] = arr[0] & arr[1]

    // Two other approaches to solve 
    // the problem
    // arr[0] = arr[1] -= arr[1];
    // arr[1] = arr[0] -= arr[0];
}

// Driver code
let First_Arr = [0, 1];
MakeBothZeros(First_Arr);
document.write(First_Arr[0] + " " + 
            First_Arr[1]);

let Second_Arr = [1, 0];
MakeBothZeros(Second_Arr);
document.write(Second_Arr[0] + " " + 
            Second_Arr[1]);

let Thrd_Arr = [0, 0];
MakeBothZeros(Thrd_Arr);
document.write(Thrd_Arr[0] + " " + 
            Thrd_Arr[1]);
            
// This code is contributed by Samim Hossain Mondal.
</script>

0 0
0 0
0 0

Time Complexity: O(1), the code will run in a constant time.
Auxiliary Space: O(1), no extra space is required, so it is a constant.

Note:
Time complexity is O(1) since just one statement is used.

3. By using the negation (!) operator (logical NOT):

In this approach, the assignment operator is used with a negation operator to make both elements of the given array 0 in a single line of code.

Approach:

There are three ways to do this:

1. arr[!arr[0]] = arr[arr[0]]
If arr={0, 1} then index 1 is assigned the index 0 value.
If arr={1, 0} then index 0 is given the index 1 value.

2. arr[arr[1]] = arr[!arr[1]]
If arr={0, 1} then index 0 value is assigned to the index 1.
If arr={1, 0} then index 1 value is assigned to the index 0.

3. arr[!arr[0]] = arr[!arr[1]]
If arr={0, 1}, since 1 is the value at index 1, the index 0 value which is 0 again,  
will be assigned to index 1, making array full of zeros.
If arr={1, 0} then index 1 value is assigned to the index 0.

Below is the C++ program to implement the approach:

// C++ program to set both elements
// to 0 in binary array[2].
#include <iostream>
using namespace std;

void MakeBothZeros(int arr[])
{
    arr[!arr[0]] = arr[arr[0]];

    // Two other approaches to solve
    // the problem
    // arr[arr[1]] = arr[!arr[1]]
    // arr[!arr[0]] = arr[!arr[1]]
}

// Driver code
int main()
{
    int First_Arr[] = {0, 1};
    MakeBothZeros(First_Arr);
    cout << First_Arr[0] << " " << 
            First_Arr[1] << endl;

    int Second_Arr[] = {1, 0};
    MakeBothZeros(Second_Arr);
    cout << Second_Arr[0] << " " << 
            Second_Arr[1] << endl;

    int Thrd_Arr[] = {0, 0};
    MakeBothZeros(Thrd_Arr);
    cout << Thrd_Arr[0] << " " << 
            Thrd_Arr[1] << endl;

    return 0;
}

// Java program to set both elements
// to 0 in binary array[2].
import java.util.*;

class GFG{

static void MakeBothZeros(int arr[])
{
    
    int index = arr[0] == 0?1:0;
    arr[index] = arr[arr[0]];
  
    // Two other approaches to solve
    // the problem
    // arr[arr[1]] = arr[!arr[1]]
    // arr[!arr[0]] = arr[!arr[1]]
}

// Driver code
public static void main(String[] args)
{
    int First_Arr[] = {0, 1};
    MakeBothZeros(First_Arr);
    System.out.print(First_Arr[0]+ " " +  
            First_Arr[1] +"\n");

    int Second_Arr[] = {1, 0};
    MakeBothZeros(Second_Arr);
    System.out.print(Second_Arr[0]+ " " +  
            Second_Arr[1] +"\n");

    int Thrd_Arr[] = {0, 0};
    MakeBothZeros(Thrd_Arr);
    System.out.print(Thrd_Arr[0]+ " " +  
            Thrd_Arr[1] +"\n");
}
}

// This code is contributed by shikhasingrajput 

# Python program to set both elements to 0 in binary array[2].
def MakeBothZeros(arr):
    if (arr[0] == 0):
        index = 1
    else:
        index = 0
    arr[index] = arr[arr[0]]

First_Arr = [0, 1]
MakeBothZeros(First_Arr)
print(First_Arr[0], end=" ")
print(First_Arr[1])

Second_Arr = [0, 1]
MakeBothZeros(Second_Arr)
print(Second_Arr[0], end=" ")
print(Second_Arr[1])

Thrd_Arr = [0, 0]
MakeBothZeros(Thrd_Arr)
print(Thrd_Arr[0], end=" ")
print(Thrd_Arr[1])

# This code is contributed by lokesh (lokeshmvs21).

// C# program to set both elements
// to 0 in binary array[2].
using System;

public class GFG{

static void MakeBothZeros(int []arr)
{
    
    int index = arr[0] == 0?1:0;
    arr[index] = arr[arr[0]];
  
    // Two other approaches to solve
    // the problem
    // arr[arr[1]] = arr[!arr[1]]
    // arr[!arr[0]] = arr[!arr[1]]
}

// Driver code
public static void Main(String[] args)
{
    int []First_Arr = {0, 1};
    MakeBothZeros(First_Arr);
    Console.Write(First_Arr[0]+ " " +  
            First_Arr[1] +"\n");

    int []Second_Arr = {1, 0};
    MakeBothZeros(Second_Arr);
    Console.Write(Second_Arr[0]+ " " +  
            Second_Arr[1] +"\n");

    int []Thrd_Arr = {0, 0};
    MakeBothZeros(Thrd_Arr);
    Console.Write(Thrd_Arr[0]+ " " +  
            Thrd_Arr[1] +"\n");
}
}

// This code is contributed by shikhasingrajput 

<script>

// JavaScript program to set both elements
// to 0 in binary array[2].
function MakeBothZeros(arr)
{
    arr[Number(!arr[0])] = arr[arr[0]];

    // Two other approaches to solve
    // the problem
    // arr[arr[1]] = arr[!arr[1]]
    // arr[!arr[0]] = arr[!arr[1]]
}

// Driver code
let First_Arr = [0, 1];
MakeBothZeros(First_Arr);
document.write(First_Arr[0] + " " + First_Arr[1],"</br>");

let Second_Arr = [1, 0];
MakeBothZeros(Second_Arr);
document.write(Second_Arr[0] + " " + Second_Arr[1],"</br>")

let Third_Arr = [0, 0];
MakeBothZeros(Third_Arr);
document.write(Third_Arr[0] + " " + Third_Arr[1],"</br>")

// This code is contributed by shinjanpatra

</script>

0 0
0 0
0 0

Time Complexity: O(1), the code will run in a constant time.
Auxiliary Space: O(1), no extra space is required, so it is a constant.