Show & Tell

Author: baioc

0.png

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+int fib(int n)
+{
+if (n < 2) return n;
+else return fib(n-1) + fib(n-2);
+}
+
+
+#include <stdio.h>
+#include <stdlib.h>
+int main(int argc, char const *argv[])
+{
+printf("%i\n", fib(atoi(argv[1])));
+}

1.c

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+from math import sqrt
+from sys import argv
+
+PHI = (1 + sqrt(5)) / 2 # golden ratio number
+PSI = 1 - PHI # and its complement
+
+def f(n):
+ return round((PHI**n - PSI**n) / sqrt(5))
+
+print(f(int(argv[1])))

10.py

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+let fibonacci n =
+ let rec fastFib = function
+ | 0 -> (0I, 1I)
+ | n ->
+ let fk, fk1 = fastFib (n / 2)
+ let fn = fk * (2I*fk1 - fk)
+ let fn1 = (pown fk1 2) + (pown fk 2)
+ if n % 2 = 0
+ then fn, fn1
+ else fn1, fn + fn1
+
+ let fn, _ = fastFib n in fn
+
+fsi.CommandLineArgs.[1]
+|> int
+|> fibonacci
+|> printfn "%A"

11.html

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+;; make a function that caches its past results
+(define (memoize proc)
+ (let ((cache (make-table)))
+ (define (delegate . args)
+ (let ((hit (lookup cache args)))
+ (or hit
+ (let ((result (apply proc args)))
+ (insert! cache args result)
+ result))))
+ delegate))
+
+;; GUILE specific
+(define make-table make-hash-table)
+(define lookup hash-ref)
+(define insert! hash-set!)
+
+;; example
+(define fib (memoize (lambda (n)
+ (if (< n 2) n
+ (+ (fib (- n 1))
+ (fib (- n 2)))))))
+
+(display
+ (fib
+ (string->number (list-ref (command-line) 1))))
+(newline)

12.fsx

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+from sys import argv
+
+def fib(n):
+ if n < 2:
+ return n
+ else:
+ return fib(n-1) + fib(n-2)
+
+
+print(fib(int(argv[1])))

13.scm

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+from sys import argv
+
+def fibs(n):
+ previous = 1
+ current = 0
+ for _ in range(n):
+ previous, current = current, previous + current
+ return current
+
+print('fibs:', fibs(int(argv[1])))
+
+
+def fibo(n, prev = 1, curr = 0):
+ if n <= 0:
+ return curr
+ else:
+ return fibo(n-1, curr, curr + prev)
+
+print('fibo:', fibo(int(argv[1])))

2.py

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+constexpr int fibo(int n, int prev = 1, int curr = 0)
+{
+if (n <= 0) return curr;
+else return fibo(n - 1, curr, prev + curr);
+}
+
+int main()
+{
+return fibo(40);
+}