107 lines
2.8 KiB
Rust
107 lines
2.8 KiB
Rust
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use std::collections::HashMap;
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#[derive(Debug)]
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struct Tree {
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value: u64,
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children: Vec<Tree>,
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}
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impl Tree {
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fn new(value: u64, children: Vec<u64>) -> Tree {
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let mut tree_children = Vec::with_capacity(children.len());
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for child in children {
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tree_children.push(Tree::new(child, Vec::new()));
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}
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Tree {
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value,
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children: tree_children,
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}
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}
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fn step(&mut self, square_free: &mut HashMap<u64, bool>) {
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if self.children.is_empty() {
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let xs = step_end(self.value, square_free);
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for val in xs {
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self.children.push(Tree::new(val, Vec::new()));
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}
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return;
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}
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for child in &mut self.children {
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child.step(square_free);
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}
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}
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fn longest_path(&self) -> Vec<u64> {
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if self.children.is_empty() {
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return vec![self.value];
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}
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let mut max_path = vec![];
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let mut max_length = 0;
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for child in &self.children {
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let temp = child.longest_path();
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if temp.len() > max_length {
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max_length = temp.len();
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max_path = temp;
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}
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}
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let mut retval = vec![self.value];
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retval.append(&mut max_path);
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return retval;
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}
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fn to_string(&self) -> String {
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let mut retval = format!("[{}: ", self.value);
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for child in &self.children {
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retval.push_str(&child.to_string()[..]);
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}
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retval.push(']');
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retval
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}
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fn count(&self) -> usize {
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if self.children.is_empty() {
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return 1;
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}
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return self.children.iter().fold(0, |mut sum, x| { sum += x.count(); sum });
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}
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}
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fn step_end(x: u64, square_free: &mut HashMap<u64, bool>) -> Vec<u64> {
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let mut new_xs = Vec::new();
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for d in 0..10 {
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let temp = x * 10 + d;
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if is_squarefree(temp, square_free) {
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new_xs.push(temp);
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}
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}
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return new_xs;
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}
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fn is_squarefree(n: u64, square_free: &mut HashMap<u64, bool>) -> bool {
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match square_free.get(&n) {
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Some(val) => *val,
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None => {
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let n2 = n as usize;
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for prime in primal::Primes::all().take(n2) {
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if n2 % (prime * prime) == 0 {
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square_free.insert(n, false);
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return false;
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}
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}
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square_free.insert(n, true);
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true
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}
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}
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}
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fn main() {
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let mut tree = Tree::new(0, vec![1, 2, 3, 5, 6, 7]);
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let mut square_free: HashMap<u64, bool> = HashMap::new();
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for _ in 0..10 {
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tree.step(&mut square_free);
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println!("{:?}", tree.longest_path());
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println!("{}", tree.count());
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}
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println!("{:?}", tree.to_string());
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}
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