#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void clrscr(){
    system("cls");
    for(int i=0; i<20; i++){
        printf("\n\n");
    }
}

int gasoline=100;

void StartDriving(){
    srand(time(NULL));
    int speed;
    int spent;
        clrscr();
        speed=rand()%100+1;
        if (speed<50){
            spent=20;
        }
        else if(speed>=50){
            spent=40;
        }
gasoline-=spent;
// atau gasoline=gasoline-spent
        printf("Your speed : %d km/hour\n",speed);
        printf("You have spent %d liters gasoline\n\n\n",spent);
        printf("Press enter to return to main menu..\n");
        getchar();
}

void Rest(){
    clrscr();
    if (gasoline<100){
    printf("Successfully recharge 20 liters gasoline...\n\n\n");
gasoline+=20;
    printf("Press enter to return to main menu..\n");
    }
    else if(gasoline==100){
    printf("Your gasoline is full...\n\n\n");
    printf("Press enter to return to main menu..\n");
    }
    getchar();
}

void mainMenu(){
    int menu;
    do{
        clrscr();
        printf("Your gasoline's car: %d liters\n", gasoline);
        printf("=======================\n");
        printf("1. Start driving\n");
        printf("2. Rest\n");
        printf("3. Exit\n");
        do{
            printf("Choose: "); scanf("%d",&menu); fflush(stdin);
        }while(menu<1 || menu>3);
        switch(menu){
            case 1 : StartDriving(); break;
            case 2 : Rest(); break;
        }
    }while(menu!=3);
}


int main(){
    mainMenu();
    clrscr();
    printf("                        Thank you and have a nice day.. ^^");
    getchar();
    return 0;
}