470
votes
171answers
170k views

Produce the number 2014 without any numbers in your source code

It's 2016 already, folks, go home. So, now that it's 2014, it's time for a code question involving the number 2014. Your task is to make a program that prints the number 2014, without using any of ...
393
votes
156answers
180k views

Write a program that makes 2 + 2 = 5 [closed]

Write a program that seemingly adds the numbers 2 and 2 and outputs 5. This is an underhanded contest. Your program cannot output any errors. Watch out for memory holes! Input is optional. ...
387
votes
110answers
68k views

Most creative way to display 42

Douglas Adams was born on March 11, 1952, and died when he was just 49. In honor of this wonderful writer, I challenge you to display 42 in the most creative way possible. You could print it in the ...
363
votes
185answers
54k views

Showcase your language one vote at a time

In this experimental popularity contest users will be able to showcase their favorite programming languages. However, the amount of code they are allowed to write is dependent on the number of votes ...
334
votes
36answers
58k views

American Gothic in the palette of Mona Lisa: Rearrange the pixels

You are given two true color images, the Source and the Palette. They do not necessarily have the same dimensions but it is guaranteed that their areas are the same, i.e. they have the same number of ...
330
votes
55answers
86k views

Tweetable Mathematical Art [closed]

Integer math can generate amazing patterns when laid out over a grid. Even the most basic functions can yield stunningly elaborate designs! Your challenge Write 3 Tweetable (meaning 140 characters ...
298
votes
44answers
88k views

Images with all colors

Similar to the images on allrgb.com, Make images where each pixel is a unique color (no color is used twice and no color is missing). Give a program that generates such an image, along with a ...
281
votes
141answers
161k views

I need a program where the user inputs an array of doubles and the program outputs the array sorted

Note: This question was severely edited since I first posted it here. The rules were moved to here, read them before posting any answer to understand the purpose of this. This was the first question ...
279
votes
33answers
46k views

Make it look like I'm working

Often, I find myself running a script or query that will take a significant amount of time to run. I can leave that script open and enjoy some guilt-free procrastination. Now, what if I could write ...
244
votes
7answers
23k views

Draw with your CPU

I have come across an article where students used network traffic to draw their university on the country's IPv6 graph. [image] Your goal is simple to tell, but hard to implement. Draw the text MAIL (...
231
votes
14answers
30k views

Build a Compiler Bomb

Introduction You're probably familiar with zip bombs, XML bombs, etc. Put simply, they are (relatively) small files which produce enormous output when interpreted by naïve software. The challenge ...
207
votes
5answers
14k views

Upgoat or Downgoat?

Given an image of a goat, your program should best try to identify whether the goat is upside down, or not. Examples These are examples of what the input may be. Not actual inputs Input: Output: ...
202
votes
56answers
32k views

Survival Game - Create Your Wolf

The Board The Board is a two dimensional array of cells. Cells are populated by Animals. Every day, all Animals on the Board simultaneously make one move. If two or more Animals move to the same cell,...
200
votes
180answers
29k views

Evolution of “Hello World!”

This contest is officially over, the winner is user23013. Congratulations! The challenge is to make a program that prints Hello World! to stdout. The catch is that your program must have a ...
198
votes
81answers
21k views

What? No error? [closed]

Your task is simple. Write a program that should obviously produce an error on first glance either when compiled or run, but either doesn't or produces some other unrelated error. This is a popularity ...
187
votes
448answers
40k views

“Hello, World!”

So... uh... this is a bit embarrassing. But we don't have a plain "Hello, World!" challenge yet (despite having 35 variants tagged with hello-world, and counting). While this is not the most ...
185
votes
50answers
31k views

Trolling the troll [closed]

A troll has captured you and is forcing you to write malware (defined as a program that damages the computer that runs it). The troll can read and understand code, but is not so good at spotting bugs. ...
182
votes
33answers
27k views

Paint Starry Night, objectively, in 1kB of code

Below is a 386x320 png representation of van Gogh's Starry Night. Your goal is to reproduce this image as closely as possible, in no more than 1024 bytes of code. For the purposes of this challenge,...
182
votes
55answers
57k views

We're no strangers to code golf, you know the rules, and so do I

Write the shortest program that prints the entire lyrics of "Never Gonna Give You Up" by Rick Astley. Rules: Must output the lyrics exactly as they appear in the above pastebin. Here's the raw dump:...
178
votes
12answers
16k views

DISARM THE B.O.M.B.!

You have been hired for your tech knowledge as a Secret Agent's sidekick to ensure that the good guy can get his job done and the world can be saved. This is your last mission before retiring with a ...
171
votes
57answers
63k views

Code that will only execute once

Goal The goal of this challenge is to write code that will execute once and only once. This means basically that it damages the program, script, or environment in some way. If rebooting the system ...
164
votes
21answers
11k views

Fibonacci Sequence Generator [closed]

Can you create a clever or unexpected Fibonacci generator? Your code must print or return either the nth Fibonacci number or the first n Fibonacci numbers.
163
votes
68answers
29k views

Print every character your program doesn't have

Your task is to build a program (using only printable ASCII characters and/or tabs and newlines) that prints out exactly the characters in the printable ASCII space (0x20 to 0x7e) that don't appear in ...
156
votes
38answers
20k views

Write program in your favorite language in another language [closed]

The determined Real Programmer can write Fortran programs in any language. from Real Programmers Don't Use Pascal Your task is to write program in your programming language of choice, but you are ...
155
votes
201answers
29k views

The Programming Language Quiz

Congratulations to Dennis who won both the cops' and the robbers' challenge! Calvin's Hobbies has already delivered on his promise and wrote this challenge for Dennis for winning the robbers' ...
147
votes
116answers
43k views

Weirdest way to produce a stack overflow [closed]

As a programmer you certainly know the error of a stack overflow due to an obvious recursion. But there are certainly many weird and unusual ways to get your favourite language to spit that error out. ...
145
votes
56answers
33k views

Debunking Stroustrup's debunking of the myth “C++ is for large, complicated, programs only”

Stroustrup has recently posted a series of posts debunking popular myths about C++. The fifth myth is: “C++ is for large, complicated, programs only”. To debunk it, he wrote a simple C++ program ...
142
votes
9answers
21k views

Draw an Image as a Voronoi Map

Credits to Calvin's Hobbies for nudging my challenge idea in the right direction. Consider a set of points in the plane, which we will call sites, and associate a colour with each site. Now you can ...
141
votes
57answers
13k views

Caveman Duels (or: Me poke you with sharp stick)

Caveman mad. Other caveman take stick but stick was for me. Caveman fight! Description Caveman need sharp stick to stab other caveman. Other caveman also try to stab with sharp stick. Caveman can ...
138
votes
103answers
31k views

Tips for golfing in Python

What general tips do you have for golfing in Python? I'm looking for ideas which can be applied to code-golf problems and which are also at least somewhat specific to Python (e.g. "remove comments" is ...
138
votes
95answers
29k views

Programming Languages Through The Years

In this challenge, users will take turns completeing three fairly simple coding tasks in programming languages that are allowed to be progressively older. The first answer must use a programming ...
133
votes
63answers
20k views

Make your language unusable

Try to write some code in your language and make it not satisfying our criteria of being a programming language any more. A language satisfies our criteria (simplified version for this challenge) of ...
133
votes
98answers
12k views

What is the smallest positive base 10 integer that can be printed by a program shorter (in characters) than itself?

I think the question as above is clear, but just in case: Write a full program (not just a function) which prints a positive base 10 integer, optionally followed by a single newline. Qualifying ...
133
votes
19answers
15k views

Do you want to code a snowman?

Here is a simple ASCII art snowman: _===_ (.,.) ( : ) ( : ) Let's make him some friends. This will be the general pattern for our ASCII art snowpeople: HHHHH HHHHH X(LNR)Y X(TTT)Y (BBB) The ...
127
votes
120answers
46k views

Don't google “google”

We all know that if you google the word "google" it will break the internet. Your task is to create a function that accepts 1 string and returns its length, in as few amount of Unicode characters as ...
126
votes
73answers
15k views

I'm not the language you're looking for!

Isn't it annoying when you find a piece of code and you don't know what language it was written in? This challenge attempts to somewhat solve this. Challenge You will have to write a program that ...
125
votes
12answers
25k views

Emulate an Intel 8086 CPU

Note: A couple of answers have arrived. Consider upvoting newer answers too. Java from NeatMonster Javascript from crempp C from Mike C C++ from Darius Goad Postscript from luser droog C++ from ...
124
votes
20answers
81k views

How slow is Python really? (Or how fast is your language?)

I have this code which I have written in Python/NumPy from __future__ import division import numpy as np import itertools n = 6 iters = 1000 firstzero = 0 bothzero = 0 """ The next line iterates ...
120
votes
240answers
23k views

Unscramble the Source Code

Note: This challenge is now closed to new cop submissions. This is to ensure that no one can post submissions that only remain uncracked because there aren't enough robbers interested in the challenge ...
113
votes
22answers
7k views

Red vs. Blue - Pixel Team Battlebots

This contest is officially over. The Blue Team won! I autoran two sets of 50 battles and amazingly, Blue won all 100 of them. Looking at the stats, it is clear that the cooperative entries of ...
112
votes
7answers
22k views

So obviously, P = NP [closed]

SAT is the problem of determining whether a boolean expression can be made true. For example, (A) can be made true by setting A=TRUE, but (A && !A) can never be true. This problem is known to ...
110
votes
92answers
17k views

Good Versus Evil

Results - July 19, 2014 The current King of the Hill is Mercenary by user Fabigler! Keep submitting entries and knock him off of his throne! Click here to view the Scoreboard. Programs submitted on ...
108
votes
174answers
22k views
+200

Is this number a prime?

Believe it or not, we do not yet have a code golf challenge for a simple primality test. While it may not be the most interesting challenge, particularly for "usual" languages, it can be nontrivial in ...
107
votes
65answers
18k views

Random script that isn't actually random

As a little joke in the office someone wanted a script that randomly picks a name, and said person will make a round of drinks. Let's call the people John, Jeff, Emma, Steve and Julie. I thought it ...
106
votes
51answers
26k views

Draw the Olympic Games logo [closed]

Challenge Draw the Olympic Games logo... ...as character (e.g. ASCII) art! Sample Output * * * * * * * * * * * * * * ...
105
votes
24answers
12k views

Lab Rat Race: an exercise in genetic algorithms

This is Fortnightly Challenge #3. Theme: Genetic Algorithms This challenge is a bit of an experiment. We wanted to see what we could do, challenge-wise, with genetic algorithms. Not everything may be ...
104
votes
27answers
8k views

Making Future Posts Runnable Online with Stack Snippets

Stack Snippets were recently added to PPCG! Reminiscent of JSFiddle, Stack Snippets allow HTML, CSS, and JavaScript to be run directly in posts! Here is a very simple Stack Snippet: alert('This ...
99
votes
1answer
2k views

“KNOT” or “NOT”?

Write a program that processes an ASCII art representation of a tangled string and decides whether or not it can be untangled into a simple loop. The tangle is represented using the characters - and | ...
98
votes
31answers
10k views

What Doesn't Kill Me…

Overview This is a bot battle to see who can survive the longest. These bots increase their power by being attacked, though, so you need to think carefully before you shoot. Each turn, you can ...
96
votes
94answers
26k views

Obfuscated Hello World

Create the shortest possible obfuscated program that displays the text "Hello World". In order to be considered an obfuscated program, it must meet at least two of the following requirements: ...

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