qddddr

/*
 * problem: https://oeis.org/A013990
 * algorithm: naive dfs
 *
 * 4x4 =     323632 =>    0.031s
 * 5x4 =   11171466 =>    1.456s
 * 5x5 = 1086297184 => 2m29.479s
 */

#include <iostream>

qddddr

import cProfile

M = 10 ** 10

# O(n)
def fibonacci_naive(n):
    a, b = 0, 1
    while 0 < n:
        a, b = b, (a + b) % M
        n -= 1

qddddr

;; http://www.gizmodo.jp/2015/05/8_39.html

(use srfi-1)
(use util.combinations)

;; a + 13 * b / c + d + 12 * e - f - 11 + g * h / i - 10
(define (F a b c d e f g h i)
  (- (/ (* (+ (- (- (* (+ (+ (/ (* (+ a 13) b) c) d) 12) e) f) 11) g) h) i) 10))

(define (G a b c d e f g h i)

qddddr

/*
 * Project Euler - Problem 255
 *
 * $ ulimit -s unlimited
 * $ g++ -std=c++11 -O4 -Wall 255.cpp; time ./a.out
 * real	0m1.061s
 * user	0m1.008s
 * sys	0m0.052s
 */

qddddr

#!r6rs

;; Project Euler - Problem 255
;;
;; $ time racket 255.sps
;; real	0m11.414s
;; user	0m11.152s
;; sys	0m0.260s

qddddr

/*
 * Project Euler - Problem 474
 * DP
 *
 * $ g++ -std=c++11 -O4 -Wall 474.cpp; time ./a.out
 * real	6m23.790s
 * user	6m23.478s
 * sys	0m0.008s
 */

qddddr

/*
 * Project Euler - Problem 457
 * Quadratic sieve + exgcd
 *
 * $ g++ -std=c++11 -O4 -Wall 457.cpp; time ./a.out
 * real	0m2.836s
 * user	0m2.793s
 * sys	0m0.040s
 */

qddddr

/*
 * compute sigma[k=1..N] eulerphi(k)
 * http://oeis.org/A064018
 * http://stackoverflow.com/a/1134851
 */

#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>

qddddr

#include <iostream>
#include <cinttypes>

using namespace std;

void display(double d)
{
  const uint64_t u = *reinterpret_cast<uint64_t*>(&d);

  const auto sign = u >> 63;

qddddr

#include <iostream>
#include <vector>
#include <cmath>

using namespace std;

const int N = 1e5;

vector<int> primes;