yanfeng42

'use strict';

/* Sample
 forward :8087/jenkins to :8080/jenkins.

In product,the entityPort can be 80,so u can access jenkins
by http://yourhostname/jenkins
Good Luck! All Done Just By NodeJS!
 */

yanfeng42

(define (count-change amount)
    (cc amount 5 0)
)

(define (cc amount kinds-of-coins depth)
    (define from-node (cc-node-depth amount kinds-of-coins depth))
    (display (cc-node-depth-label amount kinds-of-coins depth))
    (cond 
            ((= amount 0) 1) 
            ((or (< amount 0) (= kinds-of-coins 0)) 0)

yanfeng42

(define (count-change amount)
    (cc amount 5 0)
)

(define (cc amount kinds-of-coins depth)
    (define from-node (cc-node-depth amount kinds-of-coins depth))
    (display (cc-node-depth-label amount kinds-of-coins depth))
    (cond 
            ((= amount 0) 1) 
            ((or (< amount 0) (= kinds-of-coins 0)) 0)

yanfeng42

(define logB 
    (lambda (x B) 
      (/ (log x) (log B))))

(define (log3 x)
    (logB x 3)
)

; (log3 9) -> 2.0

yanfeng42

; ref: http://community.schemewiki.org/?sicp-ex-1.17
(define (fast-mult-by-add a b) 
   (define (double x) (+ x x)) 
   (define (halve x) (/ x 2)) 
    
   (define (helper a b product) ;; "add a" b times 
     (cond ((= b 0) product) 
           ((even? b) (helper (double a) (halve b) product)) 
           (else (helper a (- b 1) (+ a product))))) 
   (helper a b 0)) 

yanfeng42

	final class SampleReply: Codable {
		let code: Int32 // 状态码
		private let _pageToken: String
		lazy var pageToken: Int64 = { return Int64(self._pageToken) ?? 0 }()
		
		private enum CodingKeys: String, CodingKey {
			case code
			case _pageToken = "pageToken"
		 }
	}

yanfeng42

(define (my-gcd a b)
    (if (= b 0)
        a
        (gcd b (remainder a b)))
)

yanfeng42

(define (p) (p))

(define (test x y)
    (if (= x 0)
        0
        y)
)

; 应用序求值(先求值参数而后应用), 会陷入死循环; 正则序求值(完全展开而后归约), 会输出0.
(test 0 (p)) 

yanfeng42

;费马小定理: 如果 n 是一个素数, a是小于n 的任意正整数, 那么 a的n次方 与 a 模n同余(除以 n 的余数相同).
;  计算一个数的幂, 对另一个数取模的结果.
(define (fermat-test n)
    (define (try-it a)
        ; 因为 a 小于n, 所以 a/n 的余数就是 a.
        (= (expmode a n n) a)
    )
    (try-it (+ 1 (random (- n 1))))
)

yanfeng42

; 书上的初版实现
(define (expmode base exp m)
    (cond ((= exp 0) 1)
          ((even? exp)
            (remainder (square (expmode base (/ exp 2) m)) m))
          (else 
            (remainder (* base (expmode base (- exp 1) m)) m))
    )
)