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297 | use std::time;
extern crate rand;
use rand::Rng;
use std::env;
static mut RAIL: Vec<usize> = Vec::new();
static mut TOP: usize = 0;
fn raw_brute_prime(p: i32) -> bool {
for i in 2..f64::sqrt(p as f64).round() as i32 + 1 {
//TST[4] += 1;
if p % i == 0 {
return false;
}
}
return true;
}
fn brute_prime(p: usize, lock: usize) -> bool {
for i in 2..lock {
if p % i == 0 {
return false;
}
}
return true;
}
unsafe fn primeband(n: usize, lock: usize) -> bool {
let mut prime_count: usize = 0;
let mut e: usize; let mut j: usize;
let mut v: Vec<usize> = (2..n+1).collect();
//Lock is TOP bound, sqrt n as usize + 1
//Pass through the band
for i in 0..lock { //Early exit with square root.
//e not prime = there exits a and b whith axb = e, then a or b are <= sqrt(e).
e = v[i];
if e != 0 {
prime_count += 1;
j = e + i;
while j < n - 1 { //bounce from value to value.
v[j] = 0;
j += e;
}
}
}
//railh.reserve(prime_count);
RAIL.reserve(prime_count * 2); //By all means not the right amount.
for i in 0..n-1 { //All != 0 are primes.
e = v[i];
if e != 0 {
RAIL.push(e);
}
}
TOP = n;
return RAIL.last().unwrap() == &n;
//return railh.contains(&n);
}
unsafe fn extendedprimeband(n: usize, lock: usize) -> bool {
//Primeband, but takes in account the already existing prime list.
//let bottom;
match RAIL.last() { //Nothing to process?
Some(i) => {if i >= &n { return false; }}, // else { bottom = *i; }
None => return primeband(n, lock),
}
let mut prime_count: usize = 0;
let mut e: usize; let mut j: usize;
let mut v: Vec<usize> = (TOP+1..n+1).collect(); //fill the band. values from TOP+1 to n incuded.
//let lock = f64::sqrt(n as f64).round() as usize + 1; //TOP bound for calculations; cf primeband.
//First pass: the original band.
let mut g = 0; e = RAIL[0];
while g < RAIL.len() - 1 && e <= lock {
e = RAIL[g];
j = e - (TOP + 1) % e; //sets staring point.
//option 2 for setting starting point: (should by all means be slower)
/*j = 0;
while j < v.len() && (v[j] == 0 || v[j] % e != 0) {
j += 1;
}*/
while j < v.len() {
v[j] = 0;
j += e;
}
g += 1;
}
//Second pass: extending the band using an adaptation of erathosthene's method
//Not exacty sure of how that part works, not going to question it.
//g = 0; while g < v.len() && v[g] <= lock //the other option, slower apparently. Again not sure why or how but hey.
for i in 0..f64::sqrt(v.len() as f64).round() as usize + 1 {
e = v[i];
if e != 0 {
prime_count += 1;
j = e + i;
while j < v.len() {
v[j] = 0;
j += e;
}
}
}
RAIL.reserve(prime_count * 2); //Not enough, but a start.
for i in 0..v.len() { //All != 0 are primes.
e = v[i];
if e != 0 {
RAIL.push(e);
}
}
TOP = n;
return RAIL.last().unwrap() == &n;
}
unsafe fn resolve_band(p: usize, lock: usize) -> bool {
//where TOP < p <= TOP * TOP, RAIL not empty.
let mut i: usize = 0; let mut e = RAIL[0];
while i < RAIL.len() && e <= lock {
e = RAIL[i];
if p == RAIL[i] { return true; } //doubles as a fastcheck.
if p % e == 0 {
return false;
}
i += 1;
}
return true;
}
/* Not a good tradeoff.
unsafe fn fastcheck(p: usize) -> bool {
for i in 0..RAIL.len() {
if p == RAIL[i] { return true; }
if p < RAIL[i] { return false; }
}
return false;
}*/
unsafe fn resolve(p: usize) -> bool { //Damn you and your I32 >:(
//assumed that p > 1.
let lock = f64::sqrt(p as f64) as usize;
if TOP == 0 {
return primeband(p, lock);
} else if TOP >= lock {
return resolve_band(p, lock);
} else if TOP <= p * p {
return extendedprimeband(lock * 2, f64::sqrt(lock as f64) as usize);
} else { //Outside of the scope of this project.
return brute_prime(p, lock);
}
}
fn entry(p: i32) -> bool {
if p < 2 { return false; }
unsafe {
return resolve(p as usize);
}
}
fn test_compare(r: i32) {
let mut cha: Vec<i32> = Vec::new();
let mut chb: Vec<i32> = Vec::new();
/*for i in 2..r {
//assert_eq!(entry(i), raw_brute_prime(i));
if entry(i) != raw_brute_prime(i) {
println!("ono {}", i);
}
}*/
let mut t = time::Instant::now();
for i in 2..r {
if entry(i) {
cha.push(i);
}
}
let da = time::Instant::now() - t;
t = time::Instant::now();
for i in 2..r {
if raw_brute_prime(i) {
chb.push(i);
}
}
let db = time::Instant::now() - t;
for i in 0..cha.len() {
if cha[i] != chb[i] {
println!("{} {}", cha[i], chb[i]);
}
}
println!("Brute time: {:?} Optimised time: {:?}", db, da);
if db<da {
println!("Optimised is slower than Brute.");
//println!("Optimised is {:?} times slower than Brute.", da / db);
}
}
fn test_self(r: i32) {
let t = time::Instant::now();
for i in 2..r {
entry(i);
}
let da = time::Instant::now() - t;
println!("Optimised time: {:?}", da);
}
fn test_actual_compare(r: i32, mx: i32) {
let mut cha: Vec<i32> = Vec::new();
let mut chb: Vec<i32> = Vec::new();
let mut rcx: Vec<i32> = Vec::with_capacity(r as usize);
let mut rng = rand::thread_rng();
for _ in 2..r { //That way the set is the same
rcx.push(rng.gen_range(2, mx));
}
let mut t = time::Instant::now();
for i in &rcx {
if entry(*i) {
cha.push(*i);
}
}
let da = time::Instant::now() - t;
t = time::Instant::now();
for i in &rcx {
if raw_brute_prime(*i) {
chb.push(*i);
}
}
let db = time::Instant::now() - t;
println!("Brute time: {:?} Optimised time: {:?}", db, da);
if db<da {
println!("Optimised is slower than Brute.");
}
}
fn test_actual_self(r: i32, mx: i32) {
let mut rng = rand::thread_rng();
let mut rcx: Vec<i32> = Vec::with_capacity(r as usize);
for _ in 2..r { //Generate before timing.
rcx.push(rng.gen_range(2, mx));
}
let t = time::Instant::now();
for i in rcx {
entry(i);
}
let da = time::Instant::now() - t;
println!("Optimised time: {:?}", da);
}
fn test_compare_r(r: i32) {
let mut cha: Vec<i32> = Vec::new();
let mut chb: Vec<i32> = Vec::new();
let mut t = time::Instant::now();
for i in 2..r {
if entry(r-i+2) {
cha.push(r-i+2);
}
}
let da = time::Instant::now() - t;
t = time::Instant::now();
for i in 2..r {
if raw_brute_prime(r-i+2) {
chb.push(r-i+2);
}
}
let db = time::Instant::now() - t;
for i in 0..cha.len() {
if cha[i] != chb[i] {
println!("{} {}", cha[i], chb[i]);
}
}
println!("Brute time: {:?} Optimised time: {:?}", db, da);
}
fn test_self_r(r: i32) {
//let mut cha: Vec<i32> = Vec::new();
let t = time::Instant::now();
for i in 2..r {
entry(r-i+2);
}
let da = time::Instant::now() - t;
println!("Optimised time: {:?}", da);
}
fn main() {
let args: Vec<String> = env::args().collect();
if args.len() < 3 {
println!("This program needs test_mode and range arguments. (int)");
return;
}
let mode: i32 = args[1].parse().unwrap();
let r: i32 = args[2].parse().unwrap();
if mode == 0 {
test_compare(r);
} else if mode == 1 {
test_self(r); //Should run in under 500 seconds.
} else if mode == 2 {
if args.len() < 4 {
println!("This program needs a max_value argument. (int)");
return;
}
test_actual_compare(r, args[3].parse().unwrap());
} else if mode == 3 {
if args.len() < 4 {
println!("This program needs a max_value argument. (int)");
return;
}
test_actual_self(r, args[3].parse().unwrap());
} else if mode == 4 {
test_compare_r(r);
} else if mode == 5 {
test_self_r(r);
}
}
|
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