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typesetting/csp/csp/aima-smm.rkt

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Racket

#lang br
(require "aima.rkt")
; SEND
;+ MORE
;------
; MONEY
(define (word-value . xs)
(for/sum ([(x idx) (in-indexed (reverse xs))])
(* x (expt 10 idx))))
(define vs '(s e n d m o r y))
(define vds (for/list ([k vs])
($vd k (range 10))))
(define (not= x y) (not (= x y)))
(define alldiffs
(for/list ([pr (in-combinations vs 2)])
($constraint pr not=)))
(define smm (make-csp vds (append
alldiffs
(list
($constraint '(s) positive?)
($constraint '(m) positive?)
($constraint '(d e y) (λ (d e y) (= (modulo (+ d e) 10) y)))
($constraint '(n d r e y) (λ (n d r e y)
(= (modulo (+ (word-value n d) (word-value r e)) 100)
(word-value e y))))
($constraint '(e n d o r y) (λ (e n d o r y)
(= (modulo (+ (word-value e n d) (word-value o r e)) 1000) (word-value n e y))))
($constraint '(s e n d m o r y) (λ (s e n d m o r y)
(= (+ (word-value s e n d) (word-value m o r e))
(word-value m o n e y))))))))
(parameterize ([current-select-variable mrv]
[current-order-values lcv]
[current-inference mac])
(time (solve smm)))
(nassigns smm)
(nchecks smm)
(reset! smm)