(defun read-txt-numbers (file-name)
(let (num-lst)
(with-temp-buffer
(insert-file-contents-literally file-name)
(goto-char (point-min))
(while (re-search-forward "[0-9]+" nil t)
(setq num-lst (cons (string-to-number (match-string 0)) num-lst)) ))
(nreverse num-lst) ))
(defun make-triangle (lst)
(let (rst (n 1))
(while lst
(let ((i 0) (tmp (make-vector n 0)))
(while (< i n)
(aset tmp i (car lst))
(setq i (1+ i))
(setq lst (cdr lst)) )
(setq rst (cons tmp rst)) )
(setq n (1+ n)))
(nreverse rst) ))
(defun next-step (previous-sum-vec current-vec)
(let* ((len (length current-vec))
(current-sum-vec (make-vector len 0))
(larger-sum 0))
(dotimes (i len current-sum-vec)
(setq larger-sum
(cond
((eq i 0) (aref previous-sum-vec i))
((eq i (1- len)) (aref previous-sum-vec (1- i)))
(t (max (aref previous-sum-vec i) (aref previous-sum-vec (1- i)))) ))
(aset current-sum-vec i (+ (aref current-vec i) larger-sum)) )))
(let* ((triangle (make-triangle (read-txt-numbers (car argv))))
(previous-sum-vec (car triangle))
(current-vec))
(princ triangle)
(setq triangle (cdr triangle))
(while triangle
(setq current-vec (car triangle))
(setq previous-sum-vec (next-step previous-sum-vec current-vec))
(setq triangle (cdr triangle)) )
(princ (apply #'max (append previous-sum-vec nil)))
(princ "\n") )
メモ
- triangle.txt を用意して, 次のコマンドを実行.
emacs -script 18.el triangle.txt
- ベクトルを list に変換するときは, append で nil をくっつければOK.
(append [1 2 3] nil)
