Conditionally assign a value without using conditional and arithmetic operators

Given 4 integers a, b, y, and x, where x can assume the values of either 0 or 1 only. The following question is asked:

If 'x' is 0, 
   Assign value 'a' to variable 'y' 
Else (If 'x' is 1)
   Assign value 'b' to variable 'y'.

Note: – You are not allowed to use any conditional operator (including the ternary operator) or any arithmetic operator (+, -, *, /).

Examples :

Input :  a = 5 , b = 10, x = 1
Output :  y = 10

Input : a = 5, b = 10 , x = 0
Output :  y = 5

Asked in: Google Interview 

Solution 1:

An Idea is to simply store both ‘a’ and  ‘b’ in an array at 0th and 1st index respectively. Then store value to ‘y’ by taking ‘x’ as an index.

Below is the implementation of the above approach:

C++

// C/C++ program to assign value to y according
// to value of x

#include <iostream>
using namespace std;

// Function to assign value to y according
// to value of x
int assignValue(int a, int b, int x)
{
    int y;
    int arr[2];

    // Store both values in an array
    // value 'a' at 0th index
    arr[0] = a;

    // Value 'b' at 1th index
    arr[1] = b;

    // Assign value to 'y' taking 'x' as index
    y = arr[x];

    return y;
}

// Driver code
int main()
{
    int a = 5;
    int b = 10;
    int x = 0;

    cout << "Value assigned to 'y' is "
         << assignValue(a, b, x);
    return 0;
}

Java

// Java program to assign value to y according
// to value of x

public class GFG {
    static int assignValue(int a, int b, int x)
    {
        int y;
        int arr[] = new int[2];

        // Store both values in an array
        // value 'a' at 0th index
        arr[0] = a;

        // Value 'b' at 1th index
        arr[1] = b;

        // Assign value to 'y' taking 'x' as index
        y = arr[x];

        return y;
    }

    // Driver Method
    public static void main(String[] args)
    {
        int a = 5;
        int b = 10;
        int x = 0;

        System.out.println("Value assigned to 'y' is "
                           + assignValue(a, b, x));
    }
}

Python3

# Python 3 program to assign value to
# y according to value of x

# Function to assign value to y
# according to value of x


def assignValue(a, b, x):

    arr = [0] * 2

    # Store both values in an array
    # value 'a' at 0th index
    arr[0] = a

    # Value 'b' at 1th index
    arr[1] = b

    # Assign value to 'y' taking 'x'
    # as index
    y = arr[x]

    return y


# Driver code
if __name__ == "__main__":

    a = 5
    b = 10
    x = 0

    print("Value assigned to 'y' is",
          assignValue(a, b, x))

# This code is contributed by ita_c

C#

// C# program to assign value to y according
// to value of x
using System;

public class GFG {

    static int assignValue(int a, int b, int x)
    {
        int y;
        int[] arr = new int[2];

        // Store both values in an array
        // value 'a' at 0th index
        arr[0] = a;

        // Value 'b' at 1th index
        arr[1] = b;

        // Assign value to 'y' taking 'x'
        // as index
        y = arr[x];

        return y;
    }

    // Driver Code
    public static void Main()
    {
        int a = 5;
        int b = 10;
        int x = 0;

        Console.Write("Value assigned to "
                      + "'y' is " + assignValue(a, b, x));
    }
}

// This code is contributed by nitin mittal.

PHP

<?php
// PHP program to assign value
// to y according to value of x

// Function to assign value
// to y according to value of x
function assignValue($a, $b, $x)
{
    $y;
    $arr = array(0, 0);

    // Store both values in an array
    // value 'a' at 0th index
    $arr[0] = $a;

    // Value 'b' at 1th index
    $arr[1] = $b;

    // Assign value to 'y'
    // taking 'x' as index
    $y = $arr[$x];

    return $y;
}

// Driver code
$a = 5;
$b = 10;
$x = 0;

echo "Value assigned to 'y' is " .
        assignValue($a, $b, $x);

// This code is contributed by Anuj_67
?>

Javascript

<script>
// javascript program to assign value to y according
// to value of x


    function assignValue(a , b , x) {
        var y;
        var arr = Array(2);

        // Store both values in an array
        // value 'a' at 0th index
        arr[0] = a;

        // Value 'b' at 1th index
        arr[1] = b;

        // Assign value to 'y' taking 'x' as index
        y = arr[x];

        return y;
    }

    // Driver Method

        var a = 5;
        var b = 10;
        var x = 0;

        document.write("Value assigned to 'y' is "
        + assignValue(a, b, x));

// This code is contributed by todaysgaurav
</script>

Output

Value assigned to 'y' is 5

Solution 2: 

Using bitwise AND operator.

C++

// C/C++ program to assign value to y according
// to value of x

#include <iostream>
using namespace std;

// Driver Code
int main()
{
    int a = 5;
    int b = 10;
    int x = 1;
    int y;

    if (x & 1)
        y = b;
    else
        y = a;
    cout << "Value assigned to 'y' is " << y << endl;
    return 0;
}

Java

// Java program to assign value to y according
// to value of x
import java.io.*;
class GFG
{

  // Driver Code
  public static void main (String[] args)
  {
    int a = 5;
    int b = 10;
    int x = 1;
    int y;
    if ((x & 1) != 0)
      y = b;
    else
      y = a;
    System.out.println("Value assigned to 'y' is " + y);
  }
}

// This code is contributed by avanitrachhadiya2155

Python3

# Python3 program to assign value to y
# according to value of x

# Driver Code
a = 5
b = 10
x = 1
y = 0

if ((x & 1) != 0):
    y = b
else:
    y = a

print("Value assigned to 'y' is ", y)

# This code is contributed by ab2127

C#

// C# program to assign value to y according
// to value of x
using System;
public class GFG
{

  // Driver Code
  static public void Main ()
  {

    int a = 5;
    int b = 10;
    int x = 1;
    int y;
    if ((x & 1) != 0)
      y = b;
    else
      y = a;
    Console.WriteLine("Value assigned to 'y' is " + y);
  }
}

// This code is contributed by rag2127

Javascript

<script>

// Javascript program to assign value to y according
// to value of x

    // Driver Code

        var a = 5;
        var b = 10;
        var x = 1;
        var y;
        if ((x & 1) != 0)
            y = b;
        else
            y = a;
        document.write("Value assigned to 'y' is " + y);

// This code contributed by Rajput-Ji

</script>

Output

Value assigned to 'y' is 10

Reference: https://www.careercup.com/question?id=5135296679116800