posted on 2008-01-30 19:26:42

Okay. So, I didn't get the week 2 recap posted last Friday and I'm not getting it posted today either. Before you folks go judging me and deciding I turned into a lazy bum I thought I should make some note of progress.As I've mentioned, SICP isn't going as fast as I hoped but I won't skip a thing. If my schedule goes out the window so be it but this book is getting finished. Of course, hopefully I can conform somewhat to the schedule as well. There will be an update this weekend even if I'm not through section 1.2.

In the meantime, I thought that I'd post up something I've been working on during my lunch hour. Namely, Project Euler code. Project Euler is a website that has about 180 Programming Problems of escalating difficult. I've only devoted one lunch hour to it so far but it's been fun and I'd love to get through a quarter to half the problems this year.

The challenge for me I think will come from the math side as well as the programming and some of these I just won't be able to solve for a while. Better to challenge myself from both ends, right? The code's hidden behind a cut for those who don't want their eyes scarred by this programming nonsense. Also, I'll be improving these as I discover better programming formalisms. I'm also solving each problem in both C and Scheme. I want to solve each problem from two paradigms (or more) if possible.

Problem 1 in C:

//Project Euler Problem 1:

//Sum the numbers below 1000 divisible by 3 or 5.

#include

int main (void)

{

int count;

int sum = 0;

for (count = 1; count < 1000; count++){

if ((count % 3 == 0) || (count % 5 == 0))

sum += count;}

printf ("The sum of all multiples of 3 or 5 below 1000 is %d.n", sum);

return (0);

}

Problem 1 in Scheme:

;;Project Euler Problem 1:

;;Sum the numbers below 1,000 divisible by 3 or 5.

(define (euler1 top)

(define (iter count sum)

(define (divides? n)

(or (= (modulo n 3) 0) (= (modulo n 5) 0)))

(cond ((= count top) sum)

((divides? count) (iter (+ count 1) (+ sum count)))

(else (iter (+ count 1) sum))))

(iter 1 0))

;Value: euler1

Problem 2 in C:

//Project Euler Problem 2:

//Sum the even-valued terms in the Fibonacci sequence below 1,000,000.

#include

int main (void)

{

int a = 1;

int b = 2;

int temp, sum = 0;

while (a <= 1000000){

if (a % 2 == 0){

temp = b;

b += a;

sum += a;

a = temp;}

else{

temp = b;

b += a;

a = temp;}}

printf ("The sum of the even valued Fibonacci terms below 1,000,000 is %d.n", sum);

return (0);

}

Problem 2 in Scheme:

;;Project Euler Problem 2:

;;Sum the even-valued terms in the Fibonacci sequence below 1,000,000.

(define (euler2 top)

(define (iter current sum count)

(define (fib n)

(cond ((< n 3) n)

(else (+ (fib (- n 1)) (fib (- n 2))))))

(cond ((> current top) sum)

((even? current) (iter (fib (+ count 1))

(+ sum current) (+ count 1)))

(else (iter (fib (+ count 1)) sum (+ count 1)))))

(iter 0 0 0))

;Value: euler2

That's all for now. Hope I get section 1.2 done by this weekend!