Conditionally assign a value without using conditional and arithmetic operators

Asked in: Google Interview

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 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


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 the index.
Below is implementation

// C program  to assign value to y according 
// to value of x 
  
#include<stdio.h> 
  
// 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; 
} 
  
int main() 
{ 
    int a = 5; 
    int b = 10; 
    int x = 0; 
  
printf("Value assigned to 'y' is %d", assignValue(a, b, x); 
    return 0; 
} 

Output :
Value assigned to 'y' is 5