77. Validate Configuration Register Layout

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    // Write logic using pointer access

    if (cfg->reg & (1 << 0))
    {
        if((cfg->reg & (1 << 2)) && (cfg->reg & (1 << 3)))
        {
           return 0;
        }
        else
        {
            int reserve_bits = 0;

            for(int i = 4;i <= 15; i++)
            {
                if (cfg->reg & (1 << i))
                    reserve_bits = 1;    
            }

            if(reserve_bits == 1)
                return 0;
            else
                return 1;
        }
    }
    else
    {
        return 0;
    }
}

int main() {
    ConfigRegister cfg;
    scanf("%hx", &cfg.reg);

    int result = validate_config(&cfg);
    printf("%d", result);

    return 0;
}