[easy] challenge #1
[intermediate] challenge #1
[difficult] challenge #1

[easy] challenge #2
[intermediate] challenge #2
[difficult] challenge #2

[2/11/2012] Challenge #3 [easy]
[2/11/2012] Challenge #3 [intermediate]
[2/11/2012] challenge #3 [difficult]

[2/12/2012] Challenge #4 [easy]
[2/12/2012] Challenge #4 [intermediate]
[2/12/2012] Challange #4 [difficult]

[2/12/2012] Challenge #5 [easy]
[2/13/2012] Challenge #5 [intermediate]
[2/13/2012] Challenge #5 [difficult]

[2/14/2012] Challenge #6 [easy]
[2/14/2012] Challenge #6 [intermediate]
[2/14/2012] Challenge #6 [difficult]

[2/15/2012] Challenge #7 [easy]
[2/15/2012] Challenge #7 [intermediate]
[2/15/2012] Challenge #7 [difficult]

[2/16/2012] Challenge #8 [easy]
[2/16/2012] Challenge #8 [intermediate]
[2/16/2012] Challenge #8 [difficult]

[2/17/2012] Challenge #9 [easy]
[2/17/2012] Challenge #9 [intermediate]
[2/17/2012] Challenge #9 [difficult]

[2/18/2012] Challenge #10 [easy]
[2/18/2012] Challenge #10 [intermediate]
[2/18/2012] Challenge #10 [difficult]

[2/19/2012] Challenge #11 [easy]
[2/19/2012] Challenge #11 [intermediate]
[2/19/2012] Challenge #11 [difficult]

[2/20/2012] Challenge #12 [easy]
[2/20/2012] Challenge #12 [intermediate]
[2/20/2012] Challenge #12 [difficult]

[2/21/2012] Challenge #13 [easy]
[2/21/2012] Challenge #13 [intermediate]
[2/21/2012] Challenge #13 [difficult]

[2/23/2012] Challenge #14 [easy]
[2/23/2012] Challenge #14 [intermediate]
[2/23/2012] Challenge #14 [difficult]

[2/24/2012] Challenge #15 [easy]
[2/24/2012] Challenge #15 [intermediate]
[2/24/2012] Challenge #15 [difficult]

[2/27/2012] Challenge #16 [easy]
[2/27/2012] Challenge #16 [intermediate]
[2/27/2012] Challenge #16 [difficult]

[3/4/2012] Challenge #17 [easy]
[3/4/2012] Challenge #17 [intermediate]
[3/4/2012] Challenge #17 [difficult]

[3/5/2012] Challenge #18 [easy]
[3/5/2012] Challenge #18 [intermediate]
[3/5/2012] Challenge #18 [difficult]

[3/7/2012] Challenge #19 [easy]
[3/7/2012] Challenge #19 [intermediate]
[3/7/2012] Challenge #19 [difficult]

[3/8/2012] Challenge #20 [easy]
[3/8/2012] Challenge #20 [intermediate]
[3/8/2012] Challenge #20 [difficult]

[3/9/2012] Challenge #21 [easy]
[3/9/2012] Challenge #21 [intermediate]
[3/9/2012] Challenge #21 [difficult]

[3/10/2012] Challenge #22 [easy]
[3/10/2012] Challenge #22 [intermediate]
[3/10/2012] Challenge #22 [difficult]

[3/13/2012] Challenge #23 [easy]
[3/13/2012] Challenge #23 [intermediate]
[3/13/2012] Challenge #23 [difficult]

[3/14/2012] Challenge #24 [intermediate]

[3/15/2012] Challenge #25 [easy]
[3/15/2012] Challenge #25 [intermediate]
[3/15/2012] Challenge #25 [difficult]

[3/16/2012] Challenge #26 [easy]
[3/16/2012] Challenge #26 [intermediate]
[3/16/2012] Challenge #26 [difficult]

[3/17/2012] Challenge #27 [easy]
[3/17/2012] Challenge #27 [intermediate]
[3/17/2012] Challenge #27 [difficult]

[3/20/2012] Challenge #28 [easy]
[3/20/2012] Challenge #28 [intermediate]
[3/20/2012] Challenge #28 [difficult]

[3/22/2012] Challenge #29 [easy]
[3/22/2012] Challenge #29 [intermediate]
[3/22/2012] Challenge #29 [difficult]

[3/26/2012] Challenge #30 [easy]
[3/26/2012] Challenge #30 [intermediate]
[3/26/2012] Challenge #30 [difficult]

[3/27/2012] Challenge #31 [easy]
[3/27/2012] Challenge #31 [intermediate]
[3/27/2012] Challenge #31 [difficult]

[3/28/2012] Challenge #32 [easy]
[3/28/2012] Challenge #32 [intermediate]
[3/28/2012] Challenge #32 [difficult]

[3/30/2012] Challenge #33 [easy]
[3/30/2012] Challenge #33 [intermediate]
[3/30/2012] Challenge #33 [difficult]

[3/31/2012] Challenge #34 [easy]
[3/31/2012] Challenge #34 [intermediate]
[3/31/2012] Challenge #34 [difficult]

[4/3/2012] Challenge #35 [easy]
[4/3/2012] Challenge #35 [intermediate]
[4/3/2012] Challenge #35 [difficult]

[4/5/2012] Challenge #36 [easy]
[4/5/2012] Challenge #36 [intermediate]
[4/5/2012] Challenge #36 [difficult]

[4/8/2012] Challenge #37 [easy]
[4/8/2012] Challenge #37 [intermediate]
[4/8/2012] Challenge #37 [difficult]

[4/10/2012] Challenge #38 [easy]
[4/10/2012] Challenge #38 [intermediate]
[4/10/2012] Challenge #38 [difficult]

[4/12/2012] Challenge #39 [easy]
[4/12/2012] Challenge #39 [intermediate]
[4/12/2012] Challenge #39 [difficult]

[4/16/2012] Challenge #40 [easy]
[4/16/2012] Challenge #40 [intermediate]
[4/16/2012] Challenge #40 [difficult]

[4/19/2012] Challenge #41 [easy]
[4/19/2012] Challenge #41 [intermediate]
[4/19/2012] Challenge #41 [difficult]

[4/23/2012] Challenge #42 [easy]
[4/23/2012] Challenge #42 [intermediate]
[4/23/2012] Challenge #42 [difficult]

[4/24/2012] Challenge #43 [easy]
[4/24/2012] Challenge #43 [intermediate]
[4/24/2012] Challenge #43 [difficult]

[4/25/2012] Challenge #44 [easy]
[4/25/2012] Challenge #44 [intermediate]
[4/25/2012] Challenge #44 [difficult]

[4/27/2012] Challenge #45 [easy]
[4/27/2012] Challenge #45 [intermediate]
[4/27/2012] Challenge #45 [difficult]

[4/30/2012] Challenge #46 [easy]
[4/30/2012] Challenge #46 [intermediate]
[4/30/2012] Challenge #46 [difficult]

[5/2/2012] Challenge #47 [easy]
[5/2/2012] Challenge #47 [intermediate]
[5/2/2012] Challenge #47 [difficult]

[5/4/2012] Challenge #48 [easy]
[5/4/2012] Challenge #48 [intermediate]
[5/4/2012] Challenge #48 [difficult]

[5/7/2012] Challenge #49 [easy]
[5/7/2012] Challenge #49 [intermediate]
[5/7/2012] Challenge #49 [difficult]

[5/9/2012] Challenge #50 [easy]
[5/9/2012] Challenge #50 [intermediate]
[5/9/2012] Challenge #50 [difficult]

[5/11/2012] Challenge #51 [easy]
[5/11/2012] Challenge #51 [intermediate]
[5/11/2012] Challenge #51 [difficult]

[5/14/2012] Challenge #52 [easy]
[5/14/2012] Challenge #52 [intermediate]
[5/14/2012] Challenge #52 [difficult]

[5/16/2012] Challenge #53 [easy]
[5/16/2012] Challenge #53 [intermediate]
[5/16/2012] Challenge #53 [difficult]

[5/19/2012] Challenge #54 [easy]
[5/19/2012] Challenge #54 [intermediate]
[5/19/2012] Challenge #54 [difficult]

[5/21/2012] Challenge #55 [easy]
[5/21/2012] Challenge #55 [intermediate]
[5/21/2012] Challenge #55 [difficult]

[5/23/2012] Challenge #56 [easy]
[5/23/2012] Challenge #56 [intermediate]
[5/23/2012] Challenge #56 [difficult]

[5/25/2012] Challenge #57 [easy]
[5/25/2012] Challenge #57 [intermediate]
[5/25/2012] Challenge #57 [difficult]

[5/28/2012] Challenge #58 [easy]
[5/28/2012] Challenge #58 [intermediate]
[5/28/2012] Challenge #58 [difficult]

[6/2/2012] Challenge #59 [easy]
[6/2/2012] Challenge #59 [intermediate]
[6/2/2012] Challenge #59 [difficult]

[6/4/2012] Challenge #60 [easy]
[6/4/2012] Challenge #60 [intermediate]
[6/4/2012] Challenge #60 [difficult]

[6/6/2012] Challenge #61 [easy]
[6/6/2012] Challenge #61 [intermediate]
[6/6/2012] Challenge #61 [difficult]

[6/8/2012] Challenge #62 [easy]
[6/8/2012] Challenge #62 [intermediate]
[6/8/2012] Challenge #62 [difficult]

[6/11/2012] Challenge #63 [easy]
[6/11/2012] Challenge #63 [intermediate]
[6/11/2012] Challenge #63 [difficult]

[6/13/2012] Challenge #64 [easy]
[6/13/2012] Challenge #64 [intermediate]
[6/13/2012] Challenge #64 [difficult]

[6/15/2012] Challenge #65 [easy]
[6/15/2012] Challenge #65 [intermediate]
[6/15/2012] Challenge #65 [difficult]

[6/18/2012] Challenge #66 [easy]
[6/18/2012] Challenge #66 [intermediate]
[6/18/2012] Challenge #66 [difficult]

[6/20/2012] Challenge #67 [easy]
[6/20/2012] Challenge #67 [intermediate]
[6/20/2012] Challenge #67 [difficult]

[6/22/2012] Challenge #68 [easy]
[6/22/2012] Challenge #68 [intermediate]
[6/22/2012] Challenge #68 [difficult]

[6/26/2012] Challenge #69 [easy]
[6/26/2012] Challenge #69 [intermediate]
[6/26/2012] Challenge #69 [difficult]

[6/29/2012] Challenge #70 [easy]
[6/29/2012] Challenge #70 [intermediate]
[6/29/2012] Challenge #70 [difficult]

[7/2/2012] Challenge #71 [easy]
[7/2/2012] Challenge #71 [intermediate]
[7/2/2012] Challenge #71 [difficult]

[7/4/2012] Challenge #72 [easy]
[7/4/2012] Challenge #72 [intermediate]
[7/4/2012] Challenge #72 [difficult]

[7/6/2012] Challenge #73 [easy]
[7/6/2012] Challenge #73 [intermediate]
[7/6/2012] Challenge #73 [difficult]

[7/9/2012] Challenge #74 [easy]
[7/9/2012] Challenge #74 [intermediate]
[7/9/2012] Challenge #74 [difficult]

[7/12/2012] Challenge #75 [easy] (Function Transformation)
[7/12/2012] Challenge #75 [intermediate] (Build System)
[7/12/2012] Challenge #75 [difficult] (C Preprocessor)

[7/13/2012] Challenge #76 [easy] (Title case)
[7/13/2012] Challenge #76 [intermediate] (Probability graph)
[7/13/2012] Challenge #76 [difficult] (imgur album downloader)

[7/16/2012] Challenge #77 [easy] (Enumerating Morse code sequences)
[7/16/2012] Challenge #77 [intermediate] (Last digit of factorial)
[7/16/2012] Challenge #77 [difficult] (Boggle solver)

[7/18/2012] Challenge #78 [easy] (Keyboard Locale Simulator)
[7/18/2012] Challenge #78 [intermediate] (Dependency Planner)
[7/18/2012] Challenge #78 [hard] (Maximum Forest Fire Fighting)

[7/18/2012] Challenge #79 [easy] (Counting in steps)
[7/18/2012] Challenge #79 [intermediate] (Plain PGM file viewer)
[7/18/2012] Challenge #79 [difficult] (Remove C comments)

[7/23/2012] Challenge #80 [easy] (Anagrams)
[7/23/2012] Challenge #80 [intermediate] (Poker hands)
[7/23/2012] Challenge #80 [difficult] (Multi-word anagrams)

[7/25/2012] Challenge #81 [easy] (Numerical Calculus I)
[7/25/2012] Challenge #81 [intermediate] (Local Minimization)
[7/25/2012] Challenge #81 [difficult] (Matrix Exponential)

[7/27/2012] Challenge #82 [easy] (Substring list)
[7/27/2012] Challenge #82 [intermediate] (Broken Roman Numerals)
[7/27/2012] Challenge #82 [difficult] (Bowling scores)

[7/30/2012] Challenge #83 [easy] (Long scale and short scale)
[7/30/2012] Challenge #83 [intermediate] (Indexed file search)
[7/30/2012] Challenge #83 [difficult] (Digits of the square-root of 2)

[8/1/2012] Challenge #84 [easy] (Searching Text Adventure)
[8/1/2012] Challenge #84 [intermediate] (Recursive Song)
[8/1/2012] Challenge #84 [difficult] (City-Block TSP)

[8/3/2012] Challenge #85 [easy] (Row/column sorting)
[8/3/2012] Challenge #85 [intermediate] (3D cuboid projection)
[8/3/2012] Challenge #85 [difficult] (Bitwise arithmetic)

[8/8/2012] Challenge #86 [easy] (run-length encoding)
[8/8/2012] Challenge #86 [intermediate] (Weekday calculations)
[8/8/2012] Challenge #86 [difficult] (2-SAT)

[8/10/2012] Challenge #87 [easy] (Rectangle intersection)
[8/10/2012] Challenge #87 [intermediate] (Chord lookup)
[8/10/2012] Challenge #87 [difficult] (Sokoban game)

[8/13/2012] Challenge #88 [easy] (Vigenère cipher)
[8/13/2012] Challenge #88 [intermediate] (Printing out a calendar)
[8/13/2012] Challenge #88 [difficult] (ASCII art)

[8/20/2012] Challenge #89 [easy] (Simple statistical functions)
[8/20/2012] Challenge #89 [intermediate] (Printing strings in Brainf***)'
[8/20/2012] Challenge #89 [difficult] (Coloring the United States of America)

[8/22/2012] Challenge #90 [easy] (Walkaround Rasterizer)
[8/22/2012] Challenge #90 [intermediate] (Scientific Units Calculator)
[8/22/2012] Challenge #90 [difficult] (Alien P=NP reductions)

[8/24/2012] Challenge #91 [easy] (Sleep sort)
[8/24/2012] Challenge #91 [intermediate] (Cantor's fractions)
[8/24/2012] Challenge #91 [difficult] (Chess move validation)

[8/27/2012] Challenge #92 [easy] (Digital number display)
[8/27/2012] Challenge #92 [intermediate] (Rubik's cube simulator)
[8/27/2012] Challenge #92 [difficult] (Bags and balls)

[8/30/2012] Challenge #93 [easy] (Two-Way Morse Code Translator)
[8/30/2012] Challenge #93 [intermediate] (Z-Order Encryption)
[8/30/2012] Challenge #93 [difficult] (15-puzzle)

[9/01/2012] Challenge #94 [easy] (Elemental symbols in strings)
[9/01/2012] Challenge #94 [intermediate] (Base64 conversion)
[9/01/2012] Challenge #94 [difficult] (Simple Lisp interpreter)

[9/03/2012] Challenge #95 [easy] (Reversing text in file)
[9/03/2012] Challenge #95 [intermediate] (Filler text)
[9/03/2012] Challenge #95 [difficult] (Overlapping rectangles)

[9/05/2012] Challenge #96 [easy] (Controller Chains)
[9/06/2012] Challenge #96 [intermediate] (Parsing English Values)
[9/06/2012] Challenge #96 [difficult] (Water Droplets)

[9/08/2012] Challenge #97 [easy] (Concatenate directory)
[9/08/2012] Challenge #97 [intermediate] (Sierpinski carpet)
[9/08/2012] Challenge #97 [difficult] (Markdown to HTML)

[9/15/2012] Challenge #98 [easy] (Arithmetic tables)
[9/15/2012] Challenge #98 [intermediate] (Multiple cycling)
[9/15/2012] Challenge #98 [difficult] (Reading digital displays)

[9/17/2012] Challenge #99 [easy] (Words with letters in alphabetical order)
[9/17/2012] Challenge #99 [intermediate] (Unemployment map of the United States)
[9/17/2012] Challenge #99 [difficult] (Animated unemployment map of the United States)

[9/20/2012] Challenge #100 [easy] (Sleep Cycle Estimator)
[9/20/2012] Challenge #100 [intermediate] ("Bad" Word Filter)
[9/20/2012] Challenge #100 [difficult] (Min-Max of N-Dimensional Quadratic)

[9/27/2012] Challenge #101 [easy] (Non-repeating years)
[9/27/2012] Challenge #101 [intermediate] (Image Stenography)
[9/27/2012] Challenge #101 [difficult] (Boolean Minimization)

[9/30/2012] Challenge #102 [easy] (Dice roller)
[9/30/2012] Challenge #102 [intermediate] (n-character-set strings)
[9/30/2012] Challenge #102 [difficult] (Pokémon types)

[10/13/2012] Challenge #103 [easy-difficult] (Text transformations)

[10/18/2012] Challenge #104 [Easy] (Powerplant Simulation)
[10/18/2012] Challenge #104 [Intermediate] (Bracket Racket)
[10/18/2012] Challenge #104 [Hard] (Stack Attack)

[10/20/2012] Challenge #105 [Easy] (Word unscrambler)
[10/20/2012] Challenge #105 [Intermediate] (Boolean logic calculator)
[10/20/2012] Challenge #105 [hard] (Image color analyzer)

[10/23/2012] Challenge #106 [Easy] (Random Talker, Part 1)
[10/23/2012] Challenge #106 [Intermediate] (Jugs)
[10/23/2012] Challenge #106 [Difficult] (Mongolian Grill)

[10/25/2012] Challenge #107 [Easy] (All possible decodings)
10/25/2012] Challenge #107 [Intermediate] (Infinite Monkey Theorem)
[10/25/2012] Challenge #107 [Difficult] (English Word Identifier)

[10/27/2012] Challenge #108 [Easy] (Scientific Notation Translator)
[10/27/2012] Challenge #108 [Intermediate] (Minesweeper Generation)
[10/25/2012] Challenge #108 [Difficult] (Steiner Inellipse)

[10/30/2012] Challenge #109 [Easy] Digits Check
[10/30/2012] Challenge #109 [Intermediate]
[10/30/2012] Challenge #109 [Difficult] Death Mountains

[11/3/2012] Challenge #110 [Easy] Keyboard Shift
[11/3/2012] Challenge #110 [Intermediate] Creepy Crawlies
[11/3/2012] Challenge #110 [Difficult] You can't handle the truth!

[11/6/2012] Challenge #111 [Easy] Star delete
[11/6/2012] Challenge #111 [Intermediate] The First Sudoku
[11/6/2012] Challenge #111 [Difficult] The Josephus Problem

[11/14/2012] Challenge #112 [Easy]Get that URL!
[11/14/2012] Challenge #112 [Intermediate]Date Sorting
[11/14/2012] Challenge #112 [Difficult]What a Brainf***

[11/20/2012] Challenge #113 [Easy] String-type checking
[11/20/2012] Challenge #113 [Intermediate] Text Markup
[11/20/2012] Challenge #113 [Difficult] Memory Allocation Insanity!