041 ok

041/main.rs

@@ -0,0 +1,89 @@
+use std::collections::HashSet;
+use std::collections::VecDeque;
+
+type Str = VecDeque<u8>;
+type Res = HashSet<u32>;
+
+fn pr(s: &Str) {
+    for c in s.iter() { print!("{}", c); }
+    println!("");
+}
+
+fn is_prime(k: u32) -> bool {
+    if k < 0 {
+        return false;
+    }
+    for i in 2..k {
+        if k % i == 0 {
+            return false;
+        }
+    }
+    return true;
+}
+
+fn nstr(n: u32) -> Str {
+    let mut res = Str::new();
+    let mut nn = n;
+    while nn > 0 {
+        res.push_front((nn % 10) as u8);
+        nn /= 10;
+    }
+    res
+}
+
+
+fn strn(s: &Str) -> u32 {
+    let mut res = 0;
+    for d in s.iter() {
+        res *= 10;
+        res += *d as u32;
+    }
+    res
+}
+
+
+fn test(s: &Str, hs: &mut Res) {
+    let n = strn(s);
+    if is_prime(n) {
+        //println!("{}", n);
+        hs.insert(n);
+    }
+}
+
+fn sp(s: &Str, fx: usize, k: usize) -> Str {
+    let mut res = Str::new();
+    for i in 0..fx {
+        res.push_back(s[i]);
+    }
+    res.push_back(s[k]);
+    for i in fx..s.len() {
+        if i != k { res.push_back(s[i]); }
+    }
+    res
+}
+
+fn lp(s: &Str, fx: usize, keep_first: bool, hs: &mut Res) {
+    let kf = 0; //if keep_first { 0usize } else { 1usize };
+    for k in (fx + kf)..s.len() {
+        let ss = sp(&s, fx, k);
+        //count += 1;
+        if  ss != *s || keep_first {
+            test(&ss, hs);
+        }
+        lp(&ss, fx + 1, false, hs);
+    }
+}
+
+fn main() {
+    let mut hs = HashSet::new();
+    let mut s = nstr(1234567); // manual test of length
+    let mut max = 0;
+    let m = lp(&s, 0, true, &mut hs);
+    for h in hs.iter() {
+        if *h > max {
+            max = *h;
+        }
+    }
+    println!("{}", max);
+}
+