// Source: "Software Design ...", John A Robinson, Newnes, 2004, page 79.
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
int roll(int dice[], const int num_dice);
int print_histogram(const int num_bins, const int bin_array[]);
int main()
	{
	const int max_dice = 12;
	int dice[max_dice];
	const int possible_outcomes = max_dice*6;
	int freq_counters[possible_outcomes+1];
	// Extra 1 is because outcomes will go from 1 to possible_outcomes,
	// not from 0 to possible_outcomes-1
	int num_dice;
	int num_rolls;
	int roll_cnt;
	int i;
	cout << "Enter number of dice (1 - " << max_dice << "): ";
	cin >> num_dice;
	if ((num_dice < 1)||(num_dice > max_dice))
		{
		cout << "Sorry. Can only handle between 1 and " 
			<< max_dice << " dice\n";
		return 0;
		}
	cout << "Enter number of rolls: ";
	cin >> num_rolls;
	if (num_rolls < 1)
		{
		cout << "Cannot do less than 1 roll!\n";
		return 0;
		}
	srand((int) time(NULL));	// Seed rand number generator
	for (i = 0; i < possible_outcomes+1; i++) // Initialize range of cnts
		freq_counters[i] = 0;
	for (roll_cnt = 0; roll_cnt < num_rolls; roll_cnt++)
		{
		roll(dice, num_dice);
		int sum = 0;
		for (i = 0; i < num_dice; i++)
			sum += dice[i];
		freq_counters[sum]++;
		}
	print_histogram(num_dice*6,freq_counters);
	return 1;
	}

int roll(int dice[], const int num_dice)
	{
	for (int i = 0; i < num_dice; i++)
		{
		dice[i] = rand()/(RAND_MAX/6) + 1;
		}
	return 0;
	}

int print_histogram(const int num_bins, const int bin_array[])
	{
	const int max_height = 25;	// Desired height of histogram
	const int line_length = 79;	// Length of a text line
	char outline[line_length+1];
	int i;
	// First, clear outline
	for (i = 0; i < line_length; i++)
		outline[i] = ' ';
	outline[line_length] = '\0';	// Null termination
	// Find highest peak in histogram
	int height = -1;
	for (i = 0; i < num_bins; i++)
		{
		if (bin_array[i] > height)
			height = bin_array[i];
		}
	// Now make the histogram fit in max_height:
	// On each iteration decrement the height threshold by
	// height_dec - set so histogram will occupy max_height lines
	int height_dec = height/max_height;
	if (height_dec < 1)
		height_dec = 1;
	while(height > 0)
		{
		for (i = 0; i <= num_bins; i++)
			{
			if (bin_array[i] >= height)
				outline[i] = '*';
			}
		cout << outline << '\n';
		height -= height_dec;
		}
	return 0;
	}

// Example run of the program:
// (Distribution may appear skewed when printed with variable-width font)
//
//	Enter number of dice (1 - 12): 8
//	Enter number of rolls: 9999
//	                            *
//	                           ***
//	                          *****
//	                          *****
//	                         *******
//	                         *******
//	                         *******
//	                        *********
//	                        *********
//	                        *********
//	                       ***********
//	                       ***********
//	                       ***********
//	                      *************
//	                      *************
//	                      *************
//	                     ***************
//	                     ***************
//	                     ***************
//	                    *****************
//	                    *****************
//	                   *******************
//	                  *********************
//	                  *********************
//	                *************************
//	           ************************************
//