1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modifyBit(unsigned char reg, int pos, int mode) {
    // Write your code here
    if (mode==1){
       reg |= (1 << pos);
    }
    else reg &= ~(1<<pos);
    return reg;
}

int main() {
    unsigned char reg;
    int pos, mode;
    scanf("%hhu %d %d", &reg, &pos, &mode);
    printf("%hhu", modifyBit(reg, pos, mode));
    return 0;
}

At first, mode is checked for determining if the requirement is to set or clear a bit in particular position. Then that particular bit is set/cleared depending upon the value of mode