012 begin

012/.gitignore

@@ -0,0 +1,3 @@
+primes.txt
+compute_primes
+main_basic

012/README.md

@@ -0,0 +1,5 @@
+Generate primes list before execution
+
+```
+rustc compute_primes.rs && ./compute_primes > primes.txt
+```

012/compute_primes.rs

@@ -0,0 +1,36 @@
+const SIZE: usize  = 1500000;
+type Rs = [bool; SIZE + 1];
+
+fn remove_divs(m: usize, xs: &mut Rs) {
+    let mut i = m + m;
+    while i <= SIZE {
+        xs[i] = false;
+        i += m;
+    }
+}
+
+fn get_next_p(m_from: usize, xs: &Rs) -> Option<usize> {
+    for k in (m_from + 1)..=SIZE {
+       if xs[k] { return Some(k); } 
+    }
+    return None;
+}
+
+fn main() {
+    let mut xs: Rs = [true; SIZE + 1];
+    let mut q: usize = 1;
+    let mut count = 0;
+    loop {
+        match get_next_p(q, &xs) {
+            Some(p) => { 
+                q = p; 
+                count += 1;
+                println!("{}", p);
+                if count == 500 { break; }
+            }, 
+            None => break
+        }
+        remove_divs(q, &mut xs);
+    }
+    // println!("[{}]: {}", count, q);
+}

012/main.rs

@@ -0,0 +1,34 @@
+use std::fs::File;
+use std::io::{ self, BufRead, BufReader };
+
+
+const PS_SIZE: usize = 500usize;
+
+fn get_ps() -> Vec<u32> {
+    let file = File::open("primes.txt").unwrap();
+    let lines = io::BufReader::new(file).lines();
+    return lines.map(|line| line.unwrap().parse::<u32>().unwrap())
+                .collect();    
+}
+
+fn divs_num_test(n: u32) -> u32 {
+    let mut res = 0;
+    for i in 1..n {
+        if n % i == 0 { res += 1; }
+    }
+    return res;
+}
+
+fn main() {
+    let ps = get_ps();
+    let mut n = 1;
+    let mut best_dn = 1;
+    for k in 2..50000 {
+        n += k;
+        let dn = 500; //500; //divs_num(n);
+        //if dn > best_dn {
+        //    best_dn = dn;
+            //println!("[{}]{}:{}",k, n, dn);
+        //}
+    }
+}

012/main_basic.rs

@@ -0,0 +1,26 @@
+use std::fs::File;
+use std::io::{ self, BufRead, BufReader };
+
+const PS_SIZE: usize = 500usize;
+
+
+fn divs_num(n: u32) -> u32 {
+    let mut res = 0;
+    for i in 1..n {
+        if n % i == 0 { res += 1; }
+    }
+    return res;
+}
+
+fn main() {
+    let mut n = 1;
+    let mut best_dn = 1;
+    for k in 2..50000 {
+        n += k;
+        let dn = divs_num(n);
+        if dn > best_dn {
+            best_dn = dn;
+            println!("[{}]{}:{}",k, n, dn);
+        }
+    }
+}