cs-142:do-you-wanna-build-a-snowman [CS Wiki]

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+=Do you wanna build a snowman?=
+==Problem==
+*You want to play in the snow in May. So you build a machine to create snow. You want a program to calculate how much snow you’ll need in order to build 1 of 3 choices:
+**A bunch of snowballs (user gives width and count)
+**A snowman (user gives 3 widths)
+**An ideal snowman (user gives total height)
+*An ideal snowman has snowball widths proportional the total height of 1/2, 1/3, and 1/6 as per [http://qz.com/153318/the-science-behind-the-art-of-building-a-snowman/]
+==Solution==
+<code cpp>
+/*
+Test case 1:
+Input: opt 1, asdf, 1, 2  (invalid snowball count, snowball opt)
+Expected Output: reprompt, 4.18879 cub in
+Actual Output: reprompt, 4.18879 cub in
+Test case 2:
+Input: opt 2, 6, 4, 2 (snowman of user specified heights)
+Expected Output: 150.79632 cub in
+Test case 3:
+Input: opt 3, 12 (snowman of ideal proportions)
+Expected Output: 150.79632 cub in
+*/
+#include <iostream>
+#include <string>
+using namespace std;
+const double PI = 3.14159265359;
+// These must be declared before the function that calls them (e.g., main), but can be defined below
+void print_menu();
+int get_user_input(int min, int max);
+double calculate_snowball_volume(double width);
+double calculate_snowman_volume(double width1, double width2, double width3);
+int main()
+{
+	double total_volume = 0.0;
+	// prompt user for choice
+	print_menu();
+	int choice = get_user_input(1, 3);
+	// if choice is 1
+	if (choice == 1)
+	{
+		// prompt for width w and count c of snowballs
+		cout << "You chose 1. How many snowballs? ";
+		int snowball_count = get_user_input(0, INT_MAX);
+		cout << "How wide do you want your snowballs? ";
+		int snowball_width = get_user_input(0, INT_MAX);
+		// calculate volume for c snowballs of width w
+		total_volume = calculate_snowball_volume(snowball_width);
+		total_volume = total_volume * snowball_count;
+	}
+	// if choice is 2
+	else if (choice == 2)
+	{
+		// prompt for 3 widths
+		int bottom_width, mid_width, top_width;
+		cout << "Give me the bottom width: ";
+		bottom_width = get_user_input(0, INT_MAX);
+		cout << "Give me the middle width: ";
+		mid_width = get_user_input(0, INT_MAX);
+		cout << "Give me the top width: ";
+		top_width = get_user_input(0, INT_MAX);
+		// calculate volume of snowman with three widths
+		total_volume = calculate_snowman_volume(bottom_width, mid_width, top_width);
+	}
+	// if choice is 3
+	else if (choice == 3)
+	{
+		// prompt for height
+		cout << "How tall of an ideal snowman do you want? ";
+		int height;
+		height = get_user_input(0, INT_MAX);
+		// calculate volume of ideal snow man from height
+		total_volume = calculate_snowman_volume(height/2.0, height/3.0, height/6.0);
+	}
+	// Report total volume
+	cout << "Total volume of snow needed is " << total_volume << " cubic inches" << endl;
+	system("pause");
+	return 0;
+}
+/*
+	Just print the menu (doesn't read input)
+*/
+void print_menu()
+{
+	cout << "Choose from the following\n"
+		<< "1. A bunch of snowballs\n"
+		<< "2. A snowman\n"
+		<< "3. An ideal snowman\n"
+		<< "Choice: ";
+	return;
+}
+/*
+	Reads for integer input and reprompts until valid integer input is provided within range
+	@param min minimum value for range of input
+	@param max maximum value for range of input
+	@return first valid input integer
+*/
+int get_user_input(int min, int max)
+{
+	int input;
+	// read in from cin
+	cin >> input;
+	// while it's bad (non-int or not in range)
+	while (cin.fail() || input < min || input > max)
+	{
+		// send message, reprompt
+		cout << "That's bad input. Gimme a value between " << min << " and " << max << ":";
+		if (cin.fail())
+		{
+			cin.clear();
+			string dummy;
+			cin >> dummy;
+		}
+		// read again from cin
+		cin >> input;
+	}
+	return input;
+}
+/*
+	Calculate the volume of a sphere of particular width
+	@param width width of snowball to calculate volume for
+	@return volume of snowball with given width
+*/
+double calculate_snowball_volume(double width)
+{
+	double volume = 0.0;
+	// volume is 4/3 pi r^3 (note that r is half of the width)
+	volume = 4 / 3.0 * PI * pow(width/2.0, 3);
+	return volume;
+}
+/*
+	Calculate the volume of a three-ball snowman with balls of particular widths
+	@param width1 width of bottom snowball to calculate volume for
+	@param width2 width of mid snowball to calculate volume for
+	@param width3 width of top snowball to calculate volume for
+	@return volume of snowball with given width
+*/
+double calculate_snowman_volume(double width1, double width2, double width3)
+{
+	double volume = 0.0;
+	// add volume for three snowballs
+	volume += calculate_snowball_volume(width1);
+	volume += calculate_snowball_volume(width2);
+	volume += calculate_snowball_volume(width3);
+	return volume;
+}
+</code>

cs-142/do-you-wanna-build-a-snowman.txt · Last modified: 2015/05/19 12:01 by cs142ta

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