Add README and installation rules.

Makefile

@@ -24,6 +24,7 @@ else
 endif
 
 CC ?= gcc
+PREFIX ?= /usr/local
 CDOK_CFLAGS = -O2 -Wall -DGIT_VERSION='"$(GIT_COMMIT_NAME)$(GIT_DIRTY)"' \
 	      -DBUILD_DATE='"$(BUILD_DATE)"'
 
@@ -38,3 +39,9 @@ clean:
 
 %.o: %.c
 	$(CC) $(CFLAGS) $(CDOK_CFLAGS) -o $*.o -c $*.c
+
+install: cdok
+	install -m 0755 -o root -g root cdok $(DESTDIR)$(PREFIX)/bin
+
+uninstall:
+	rm -f $(DESTDIR)$(PREFIX)/bin/cdok

README

@@ -0,0 +1,143 @@
+Cdok
+====
+
+Calcudoku is a sudoku-like game invented by Tetsuya Miyamoto (marketed
+under the trademarked name "KenKen"). The following is an example of a
+6x6 calcudoku puzzle:
+
+    ╔═════╦═════╦═════╦═════╦═══════════╗
+    ║12+  ║4/   ║     ║     ║3*   ┊     ║
+    ║     ║     ║  5  ║  2  ║     ┊     ║
+    ║     ║     ║     ║     ║     ┊     ║
+    ║┈┈┈┈┈║┈┈┈┈┈╠═════╩═════╬═══════════╣
+    ║     ║     ║7+   ┊     ║60*  ┊     ║
+    ║     ║     ║     ┊     ║     ┊     ║
+    ║     ║     ║     ┊     ║     ┊     ║
+    ║┈┈┈┈┈╠═════╬═══════════╩═════╗┈┈┈┈┈║
+    ║     ║12+  ║28+  ┊     ┊     ║     ║
+    ║     ║     ║     ┊     ┊     ║     ║
+    ║     ║     ║     ┊     ┊     ║     ║
+    ╠═════╣┈┈┈┈┈╠═══════════╗┈┈┈┈┈╚═════╣
+    ║     ║     ║1-   ┊     ║     ┊     ║
+    ║  3  ║     ║     ┊     ║     ┊     ║
+    ║     ║     ║     ┊     ║     ┊     ║
+    ╠═════╣┈┈┈┈┈╚═════╦═════╣┈┈┈┈┈╔═════╣
+    ║     ║     ┊     ║11+  ║     ║2*   ║
+    ║  4  ║     ┊     ║     ║     ║     ║
+    ║     ║     ┊     ║     ║     ║     ║
+    ╠═════╩═══════════╣┈┈┈┈┈╠═════╣┈┈┈┈┈║
+    ║10+  ┊     ┊     ║     ║     ║     ║
+    ║     ┊     ┊     ║     ║  4  ║     ║
+    ║     ┊     ┊     ║     ║     ║     ║
+    ╚═════════════════╩═════╩═════╩═════╝
+
+As in sudoku, each row and each column must contain the numbers 1 to 6
+once each. Some initial values may be given. There are no sub-boxes,
+but groups of connected cells outlined in double-lines contain a clue
+in the top-left corner (e.g. "11+"). The clue consists of a target
+value and one of the characters +, -, * or /, indicating the type of
+the group:
+
+Sum: +
+
+  ~ The numbers in this group must add to the target value.
+
+Difference: -
+
+  ~ One of the numbers in this group, minus the rest, must equal the
+    target value (the number to be subtracted from may be any of the
+    cells).
+
+Product: *
+
+  ~ The numbers in this group must multiply to produce the target value.
+
+Ratio: /
+
+  ~ One of the numbers in this group, divided by all of the others,
+    must equal the target value. As in a difference group, which of
+    the cells contains the number to be divided is not specified.
+
+Numbers may be repeated within a group (so long as they're not also
+repeated within a row or column). Each puzzle has a unique
+solution. The solution to the example shown above is:
+
+    ╔═════╦═════╦═════╦═════╦═══════════╗
+    ║12+  ║4/   ║     ║     ║3*   ┊     ║
+    ║  6  ║  4  ║  5  ║  2  ║  1  ┊  3  ║
+    ║     ║     ║     ║     ║     ┊     ║
+    ║┈┈┈┈┈║┈┈┈┈┈╠═════╩═════╬═══════════╣
+    ║     ║     ║7+   ┊     ║60*  ┊     ║
+    ║  5  ║  1  ║  4  ┊  3  ║  2  ┊  6  ║
+    ║     ║     ║     ┊     ║     ┊     ║
+    ║┈┈┈┈┈╠═════╬═══════════╩═════╗┈┈┈┈┈║
+    ║     ║12+  ║28+  ┊     ┊     ║     ║
+    ║  1  ║  2  ║  6  ┊  4  ┊  3  ║  5  ║
+    ║     ║     ║     ┊     ┊     ║     ║
+    ╠═════╣┈┈┈┈┈╠═══════════╗┈┈┈┈┈╚═════╣
+    ║     ║     ║1-   ┊     ║     ┊     ║
+    ║  3  ║  6  ║  2  ┊  1  ║  5  ┊  4  ║
+    ║     ║     ║     ┊     ║     ┊     ║
+    ╠═════╣┈┈┈┈┈╚═════╦═════╣┈┈┈┈┈╔═════╣
+    ║     ║     ┊     ║11+  ║     ║2*   ║
+    ║  4  ║  3  ┊  1  ║  5  ║  6  ║  2  ║
+    ║     ║     ┊     ║     ║     ║     ║
+    ╠═════╩═══════════╣┈┈┈┈┈╠═════╣┈┈┈┈┈║
+    ║10+  ┊     ┊     ║     ║     ║     ║
+    ║  2  ┊  5  ┊  3  ║  6  ║  4  ║  1  ║
+    ║     ┊     ┊     ║     ║     ║     ║
+    ╚═════════════════╩═════╩═════╩═════╝
+
+This program, cdok, can be used to examine, print, solve and generate
+these puzzles. Puzzles are parsed in a "puzzle spec" format, where
+rows are given one per line, with cells separated by spaces. Groups
+are labelled with alphabetic characters, which are then used to
+identify cell membership. A valid puzzle spec for the example above
+is:
+
+    J+12    F/4     5       2       E*3     E
+    J       F       H+7     H       I*60    I
+    J       D+12    G+28    G       G       I
+    3       D       K-1     K       G       G
+    4       D       D       B+11    G       A*2
+    C+10    C       C       B       4       A
+
+Puzzle specs may be terminated by a blank line. Anything following the
+blank line is ignored when parsing.
+
+Installation
+------------
+
+To build cdok, type ``make``. Type ``make install`` to install the
+resulting binary.
+
+Try it out by typing ``cdok generate`` to generate a 6x6 puzzle. If
+your terminal supports UTF-8, use the ``-u`` flag to draw the puzzle
+using UTF-8 line-drawing characters.
+
+Some definitions of Calcudoku require that difference and ratio groups
+be limited to two cells (to avoid confusion due to the
+non-associativity of subtraction and division). Cdok does not impose
+this requirement in generated puzzles by default, but it will if you
+use the ``-T`` option.
+
+Type ``cdok --help`` to get a full list of options.
+
+Copyright
+---------
+
+Copyright (C) 2012 Daniel Beer <[email protected]>
+
+Permission to use, copy, modify, and/or distribute this software for
+any purpose with or without fee is hereby granted, provided that the
+above copyright notice and this permission notice appear in all
+copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.