100 lines
2.5 KiB
Rust
100 lines
2.5 KiB
Rust
/**
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* [139] Word Break
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*/
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pub struct Solution {}
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// submission codes start here
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use std::{cell::RefCell, collections::HashMap, rc::Rc};
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struct Trie {
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is_word: bool,
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next: HashMap<char, Rc<RefCell<Trie>>>,
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}
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impl Trie {
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fn new(is_word: bool) -> Rc<RefCell<Self>> {
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Rc::new(RefCell::new(Trie {
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is_word,
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next: HashMap::new(),
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}))
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}
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}
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impl Solution {
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pub fn word_break(s: String, word_dict: Vec<String>) -> bool {
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let mut root = Trie::new(false);
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// 建立字典树
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for word in &word_dict {
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let mut node = Rc::clone(&root);
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for (i, c) in word.chars().enumerate() {
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if node.borrow().next.contains_key(&c) {
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if i == word.len() - 1 {
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node.borrow().next.get(&c).unwrap().borrow_mut().is_word = true;
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}
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} else {
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if i == word.len() - 1 {
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node.borrow_mut().next.insert(c, Trie::new(true));
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} else {
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node.borrow_mut().next.insert(c, Trie::new(false));
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}
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}
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let tmp_node = Rc::clone(node.borrow().next.get(&c).unwrap());
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node = tmp_node;
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}
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}
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let word: Vec<char> = s.chars().collect();
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let n = s.len();
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let mut dp = vec![false; n];
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for i in 0..n {
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if i > 0 && !dp[i - 1] {
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continue;
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}
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let mut node = Rc::clone(&root);
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let mut pos = i;
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while pos < n && node.borrow().next.contains_key(&word[pos]) {
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let next_node = Rc::clone(node.borrow().next.get(&word[pos]).unwrap());
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dp[pos] = next_node.borrow().is_word || dp[pos];
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pos += 1;
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node = next_node;
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}
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}
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dp[n - 1]
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}
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}
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_139() {
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assert!(Solution::word_break(
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"leetcode".to_owned(),
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vec_string!("leet", "code")
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));
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assert!(Solution::word_break(
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"applepenapple".to_owned(),
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vec_string!("apple", "pen")
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));
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assert!(!Solution::word_break(
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"catsandog".to_owned(),
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vec_string!("cats", "cat", "sand", "and", "cat")
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));
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assert!(Solution::word_break(
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"aaaaaaa".to_owned(),
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vec_string!("aaa", "aaaa")
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));
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}
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}
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