jkk

;;;; Translation of Peter Norvig's sudoku solver to idiomatic Clojure
;;;; See http://norvig.com/sudoku.html
;;;;
;;;; Throughout this program we have:
;;;;   r is a row,     e.g. :a
;;;;   c is a column,  e.g. 3
;;;;   s is a square,  e.g. [:a 3]
;;;;   d is a digit,   e.g. 9
;;;;   u is a unit,    e.g. [[:a 1] [:b 1] [:c 1] ... [:i 1]]
;;;;   grid is a grid, e.g. 81 non-blank chars, e.g. starting with ".18...7..."