crypto-square: initial commit

cpp/crypto-square/README.md

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+# Crypto Square
+
+Implement the classic method for composing secret messages called a square code.
+
+The input is first normalized: The spaces and punctuation are removed
+from the English text and the message is downcased.
+
+Then, the normalized characters are broken into rows.  These rows can be
+regarded as forming a rectangle when printed with intervening newlines.
+
+For example, the sentence
+
+> If man was meant to stay on the ground god would have given us roots
+
+is 54 characters long.
+
+Broken into 8-character columns, it yields 7 rows.
+
+Those 7 rows produce this rectangle when printed one per line:
+
+```plain
+ifmanwas
+meanttos
+tayonthe
+groundgo
+dwouldha
+vegivenu
+sroots
+```
+
+The coded message is obtained by reading down the columns going left to
+right.
+
+For example, the message above is coded as:
+
+```plain
+imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn sseoau
+```
+
+Write a program that, given an English text, outputs the encoded version
+of that text.
+
+The size of the square (number of columns) should be decided by the
+length of the message.
+
+If the message is a length that creates a perfect square (e.g. 4, 9, 16,
+25, 36, etc), use that number of columns.
+
+If the message doesn't fit neatly into a square, choose the number of
+columns that corresponds to the smallest square that is larger than the
+number of characters in the message.
+
+For example, a message 4 characters long should use a 2 x 2 square. A
+message that is 81 characters long would use a square that is 9 columns
+wide.
+
+A message between 5 and 8 characters long should use a rectangle 3
+characters wide.
+
+Output the encoded text grouped by column.
+
+For example:
+
+- "Have a nice day. Feed the dog & chill out!"
+  - Normalizes to: "haveanicedayfeedthedogchillout"
+  - Which has length: 30
+  - And splits into 5 6-character rows:
+    - "havean"
+    - "iceday"
+    - "feedth"
+    - "edogch"
+    - "illout"
+  - Which yields a ciphertext beginning: "hifei acedl v…"
+
+## Getting Started
+
+Make sure you have read [the C++ page](http://exercism.io/languages/cpp) on
+exercism.io.  This covers the basic information on setting up the development
+environment expected by the exercises.
+
+## Passing the Tests
+
+Get the first test compiling, linking and passing by following the [three
+rules of test-driven development](http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd).
+Create just enough structure by declaring namespaces, functions, classes,
+etc., to satisfy any compiler errors and get the test to fail.  Then write
+just enough code to get the test to pass.  Once you've done that,
+uncomment the next test by moving the following line past the next test.
+
+```C++
+#if defined(EXERCISM_RUN_ALL_TESTS)
+```
+
+This may result in compile errors as new constructs may be invoked that
+you haven't yet declared or defined.  Again, fix the compile errors minimally
+to get a failing test, then change the code minimally to pass the test,
+refactor your implementation for readability and expressiveness and then
+go on to the next test.
+
+Try to use standard C++11 facilities in preference to writing your own
+low-level algorithms or facilities by hand.  [CppReference](http://en.cppreference.com/)
+is a wiki reference to the C++ language and standard library.  If you
+are new to C++, but have programmed in C, beware of
+[C traps and pitfalls](http://www.slideshare.net/LegalizeAdulthood/c-traps-and-pitfalls-for-c-programmers).
+
+## Source
+
+J Dalbey's Programming Practice problems [view source](http://users.csc.calpoly.edu/~jdalbey/103/Projects/ProgrammingPractice.html)