77. Validate Configuration Register Layout

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    if(cfg->reg & (1 << 0)){
        if( !((cfg->reg & (1 << 2)) && (cfg->reg & (1 << 3))) ){
            int cnt = 0;
            for(int i = 4; i <16; i++){
                if (cfg->reg & (1 << i)){
                    ++cnt;
                } 
                }
            if(cnt == 0){
                return 1;
            }
        }
    }
    return 0;
}

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

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

    return 0;
}