Problem of the Day -- Party Hat

Party Hat

Over at Problem of the Day we like to party it up. Since April is coming to a close let's create a program to prepare for all the May birthdays coming up. Today's problem is given a number, generate a party hat that many lines tall. Here is an example with 8:

       *
      ***
     *****
    *******
   *********
  ***********
 *************
***************

Permalink: http://problemotd.com/problem/party-hat/

Comments:

Tom - 10 years, 8 months ago

a java solution:

import java.util.Scanner;

public class PartyHat{
    public static void main(String [] args){
    Scanner sc = new Scanner(System.in);
    System.out.println("Enter size:");
    int size = sc.nextInt();
    System.out.println(makeHat(size));
    }

    public static String makeHat(int size){
    int layer = size;
    int count = layer - 1;
    int num = 1;
    char gap = ' ';
    char fill = '@';
    String out = "";
    while(layer > 0){
        for(int i = 0; i < count; i++){
        out += gap;
        }
        for(int j = 0; j < num; j++){
        out += fill;
        }
        out += "\n";
        num += 2;
        count--;
        layer--;
    }
    return out;
    }       
}

reply permalink

Anonymous - 10 years, 8 months ago

In brainf*ck. online interpreter

Height: ++++++++ (8)

>>++++++[<++++++>-]<++++++>++++++++++>>++++[<++++++++>-]<<<<[->>>>+>+>+<<<<<<]
>>>>>>[-<<<<<<+>>>>>>]+<-<[>[->>+>+>+<<<<]>>>>[-<<<<+>>>>]<<<<>[->>>+>+<<<<]>>
>>[-<<<<+>>>>]<<<<>[-<<<<.>>>>]>>[-<<<<<<<<.>>>>>>>>]<[-<<<<<.>>>>>]<<<<<<.>>>
->++<<-]

reply permalink

Jt - 10 years, 8 months ago

Nicely done

reply permalink

Anonymous - 10 years, 8 months ago

class Program
{
    static void Main(string[] args)
    {
        MakePartyHat();
    }
    static void MakePartyHat()
    {
        bool blnMakeHat = true; int intPartyHatSize; string strInput;
        while (blnMakeHat)
        {
            Console.WriteLine("Party hat size?");
            strInput = Console.ReadLine();
            if (Int32.TryParse(strInput, out intPartyHatSize))
            {
                for (int i = 1; i <= intPartyHatSize; i++)
                {
                    Console.WriteLine(new String(' ', intPartyHatSize - i) + new String('*', (i * 2) - 1));
                }
            }
            if (strInput.ToLower() == "exit")
            {
                blnMakeHat = false;
            }
        }
    }
}

reply permalink

Anonymous - 10 years, 8 months ago
Nice little problem for a lazy afternoon. J:
```
partyhat=: monad define
  (- |. i. y) |."0 1 '*' $~"0 >: +: i. y
)
```
reply permalink
Daniel - 10 years, 8 months ago
I really need to start playing around with J.

reply permalink

Anonymous - 10 years, 8 months ago

It's good fun. I'm in an explainy mood today, so here's the gist of what that J snippet does:

Calculate              Generate               Determine             Rotate
star count           rows of stars            rotation             the rows

     1             '*              '             -7            '       *       '
     3             '***            '             -6            '      ***      '
     5             '*****          '             -5            '     *****     '
     7      =>     '*******        '      =>     -4     =>     '    *******    '
     9             '*********      '             -3            '   *********   '
    11             '***********    '             -2            '  ***********  '
    13             '*************  '             -1            ' ************* '
    15             '***************'              0            '***************'

reply permalink

SFF - 10 years, 8 months ago

Not as elegant as the others, but it works.

import java.util.Scanner;

class PartyHat
{
    public static void main (String[] args)
    {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter party hat size:");
        int height = scanner.nextInt();
        makeHat(height);
    }

    public static void makeHat(int height)
    {
        int width = (2 * height) - 1;
        for (int i = 1; i <= height; i++)
        {
            for(int j = 1; j <= height - i; j++)
                System.out.print(" ");
            for(int k = 1; k <= (2 * i) - 1; k++)
                System.out.print("*");
            for(int l = 1; l <= height - i; l++)
                System.out.print(" ");

            System.out.println();
        }
    }
}

reply permalink

duddles - 10 years, 8 months ago

in python:

def party_hat(n):
    for i in xrange(n):
        s = ' ' * (n - i - 1)
        s += '*' * (i*2 + 1)
        s += ' ' * (n - i - 1)
        print s

reply permalink

Anonymous - 10 years, 8 months ago
dude why would you add trailing whitespace?

reply permalink

Anonymous - 10 years, 8 months ago

public static void Main() { Console.WriteLine(PartyHat(30)); }

static string PartyHat(int height)
{
    StringBuilder sb = new StringBuilder();

    int width = 2*height-1,
    lower = width/2, 
    upper = lower;

    while(lower >= 0)
    {
        for(int i = 0; i < width; i++)
        {
            if(i >= lower && i <= upper)
                sb.Append("*");
            else
                sb.Append(" ");
        }
        sb.AppendLine();
        lower--;
        upper++;
    }
    return sb.ToString();
}

reply permalink

Jt - 10 years, 8 months ago

Trying some C++

#include "stdafx.h"
#include <iostream>
#include <sstream>

using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
  string input = "";

  while (true)
  {
    int partyHatLines = 0;

    while (true) 
    {
      cout << "Enter the number of lines you would like in your party hat, or type exit" << std::endl;
      getline(cin, input);

      if (input == "exit")
      {
        return 0;
      }

      stringstream myStream(input);
      if (myStream >> partyHatLines)
      {
        break;
      }
      cout << "Invalid number, please try again" << endl;
    }

    int partyHatSpaces = partyHatLines + (partyHatLines - 1);
    for (int index = 1; index <= partyHatLines; index++)
    {
      int starCount = index + (index - 1);
      int padCount = (partyHatSpaces - starCount) / 2;
      cout << std::string(padCount, ' ');
      cout << std::string(starCount, '*');
      cout << std::string(padCount, ' ');
      cout << std::endl;
    }
  }

  return 0;
}

reply permalink

Dustin S - 10 years, 8 months ago

Python 2.7

def partyHat(lines):
  spaces = 0
  stars = lines * 2 - 1

  output = ""
  while (numberStars > 0):
    output = " " * numberSpaces + "*" * numberStars + "\n" + output
    numberSpaces += 1
    numberStars -= 2

  return output

reply permalink

Dustin S - 10 years, 8 months ago

lol, naming issues ^{^{^}}

def partyHat(lines):
  spaces = 0
  stars = lines * 2 - 1

  output = ""
  while (stars > 0):
    output = " " * spaces + "*" * stars + "\n" + output
    spaces += 1
    stars -= 2

  return output

reply permalink

Will - 10 years, 8 months ago

Yaay more LISP! :D

(defun make-party-hat-helper (i n)
  (when (> n 0)
    (do ((j 0 (+ j 1)))
    ((= j (- n 1)))
      (format t " "))
    (do ((j 0 (+ j 1)))
    ((= j i))
      (format t "*"))
    (format t "~%")
    (make-party-hat-helper (+ i 2) (- n 1))))

(defun make-party-hat (n)
  (make-party-hat-helper 1 n))

reply permalink

Samuel Chase - 10 years, 8 months ago

Solution in Common Lisp.


(defun print-party-hat (height)
  (flet ((hat-width (line-no)
           (+ (* 2 line-no) 1)))
    (let ((line-width (hat-width height)))
      (loop for line upto height do
           (let* ((hat-width (hat-width line))
                  (half-space-width (truncate (/ (- line-width hat-width) 2))))
             (format t "~a" (make-string half-space-width :initial-element #\Space))
             (format t "~a" (make-string (hat-width line) :initial-element #\*))
             (format t "~a" (make-string half-space-width :initial-element #\Space))
             (terpri))))))

reply permalink

Byron - 10 years, 7 months ago
This might be really bad but I am just learning Python.

print("Please enter the number of rows you would like") rowcount = input(int)

starCount = 1; for x in range(0, int(rowcount)): line = ' ' * (int(rowcount) - int(x)) line += '*' * int(starCount) starCount += 2 print(line)

reply permalink

Problem of the Day A new programming or logic puzzle every Mon-Fri

Party Hat

Comments:

Problem of the Day
A new programming or logic puzzle every Mon-Fri