038 ok

038/main.rs

@@ -0,0 +1,106 @@
+use std::collections::HashSet;
+use std::collections::VecDeque;
+
+type Str = VecDeque<u8>;
+type Res = HashSet<u32>;
+
+fn take(n: usize, s: &mut Str) -> u32 {
+    let mut res = 0u32;
+    for _ in 0..n {
+        res *= 10;
+        res += s.pop_front().unwrap() as u32;
+    }
+    res
+}
+
+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 len(n: u32) -> usize {
+    let mut res = 0usize;
+    let mut nn = n;
+    while nn > 0 {
+        res += 1;
+        nn /= 10;
+    }
+    res
+}
+
+fn testn(s: &Str, n: usize) -> bool {
+    let mut ss = s.clone();
+    let k = take(n, &mut ss);
+    let mut i = 2;
+    while len(k * i) <= ss.len() {
+        let kt = take(len(k*i), &mut ss);
+        if kt != k*i { return false; }
+        i += 1;
+    }
+    ss.len() == 0
+}
+
+fn test(s: Str) -> bool {
+    for k in 1..s.len() - 4 {
+        if testn(&s.clone(), k) { return true; }
+    }
+    return false;
+}
+
+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, max: u32) -> u32 {
+    let kf = 0; //if keep_first { 0usize } else { 1usize };
+    let mut mymax = max;
+    for k in (fx + kf)..s.len() {
+        let ss = sp(&s, fx, k);
+        if  ss != *s || keep_first {
+            if test(ss.clone()) {
+                let n = strn(&ss);
+                if n > mymax { mymax = n }
+            }
+        }
+        let m = lp(&ss, fx + 1, false, mymax);
+        if m > mymax { mymax = m; }
+
+    }
+    mymax
+}
+fn main() {
+    let mut s = nstr(123456789);
+    //let mut s = nstr(192384576);
+    //let mut s = nstr(918273654);
+
+    //let mut hs = HashSet::new();
+    let m = lp(&s, 0, true, 0);
+    println!("{}", m);
+
+    //let n = strn(&s);
+    //println!("{}", n);
+    
+}