// DiceAndProbability.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "math.h"
#include "time.h"

int roll_frequency[121];
int die[21];

void roll_many_dice(int sum, int dice_count);

int _tmain(int argc, _TCHAR* argv[])
{
	int number_of_dice;
	int roll, sum;
	time_t t1;
	time_t t2;
	struct tm *tblock1;
	struct tm *tblock2;
    int start_hour, end_hour;
	int start_min, end_min;
	int start_sec, end_sec;

    // Get the number of dice user wishes to roll
	printf("Enter the number of dice you wish to roll: ");
	number_of_dice = 0;

	scanf("%d", &number_of_dice);
	while((number_of_dice <= 0) && (number_of_dice > 20)){
		printf("\a\a\a Error: Number of dice must be within 1 through 20.  Try again: ");
	    scanf("%d", &number_of_dice);
	}

	//Get the time the program starts
    t1 = time(NULL);
	tblock1 = localtime(&t1);
	start_hour = tblock1->tm_hour;
	start_min = tblock1->tm_min;
	start_sec = tblock1->tm_sec;

    //Call the recursive function 
	roll_many_dice(0, number_of_dice);

	//List the results:  frequency and probability of each roll
    for(roll=1; roll<=6*number_of_dice; roll++)
		printf("%2d Dice: roll %3d occurs with frequency: %10d, probability %7.12f\n",
		        number_of_dice, roll,roll_frequency[roll], roll_frequency[roll]/pow(6.0,number_of_dice));

    //Get the ending time of the program
	t2 = time(NULL);
	tblock2 = localtime(&t2);
	end_hour = tblock2->tm_hour;
	end_min = tblock2->tm_min;
	end_sec = tblock2->tm_sec;

    //Print the start and end time of the program for comparison
	printf("Program Start (hr:min:sec):  %2d:%2d:%2d\n", start_hour, start_min, start_sec);
	printf("Program End   (hr:min:sec):  %2d:%2d:%2d\n", end_hour, end_min, end_sec);

	//Done! Finally!
	return 0;
}

void roll_many_dice(int sum, int dice_count)
{
	int face;  // 1, 2, 3, 4, 5, or 6

    if(dice_count == 1) //...we're on the last die! almost done!
		for(face=1; face<=6; face++)
		    roll_frequency[sum+face]++; //Add the last die to the total roll

	else for(face=1; face<=6; face++)//...This isn't the last die! 
		roll_many_dice(sum+face, dice_count-1); //Recursively call the dice roll subroutine for the remaining n-1 dice

	return;
}