Conditionally assign a value without using conditional and arithmetic operators

Given 4 integers a, b, y, and x, where x can only either 0 and 1 only. The ask is as follows:

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 ternary operator) or any arithmetic operator ( +, -, *, /).


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

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

Asked in : Google Interview

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

Below is C++ implementation

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;


Value assigned to 'y' is 5

Reference :

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