A function that returns 2 for input 1 and 1 for input 2 is to be made. This function can be made in many ways based on the logic you use. The easiest way to do this is to use a conditional statement that if the number is 1 then return 2 otherwise return 1 and ways include using mathematical operations (any will do) and XOR operation.
Example
#include <stdio.h> // Method 1 using the if statement int reverseif(int x) { if (x == 1) return 2; else return 1; } // Method 2 using the subtarction form sum of the two numbers (3 in this case) int reversesub(int x){ return (3-x); } int main() { printf("%d\n", reverseif(1)); printf("%d\n", reversesub(2)); return 0; }
Output
2 1