20240806 Finished

src/problem/mod.rs

@@ -195,4 +195,5 @@ mod p69_sqrtx;
 mod p50_powx_n;
 mod p149_max_points_on_a_line;
 mod p70_climbing_stairs;
-mod p198_house_robber;
+mod p198_house_robber;
+mod p139_word_break;

src/problem/p139_word_break.rs

@@ -0,0 +1,88 @@
+/**
+ * [139] Word Break
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+use std::{rc::Rc, cell::RefCell, collections::HashMap};
+
+struct Trie {
+    is_word: bool,
+    next: HashMap<char, Rc<RefCell<Trie>>>,
+}
+
+impl Trie {
+    fn new(is_word: bool) -> Rc<RefCell<Self>> {
+        Rc::new(RefCell::new(Trie {
+            is_word,
+            next: HashMap::new(),
+        }))
+    }
+}
+
+impl Solution {
+    pub fn word_break(s: String, word_dict: Vec<String>) -> bool {
+        let mut root = Trie::new(false);
+
+        // 建立字典树
+        for word in &word_dict {
+            let mut node = Rc::clone(&root);
+
+            for (i, c) in word.chars().enumerate() {
+                if node.borrow().next.contains_key(&c) {
+                    if i == word.len() - 1 {
+                        node.borrow().next.get(&c).unwrap().borrow_mut().is_word = true;
+                    }
+                } else {
+                    if i == word.len() - 1 {
+                        node.borrow_mut().next.insert(c, Trie::new(true));
+                    } else {
+                        node.borrow_mut().next.insert(c, Trie::new(false));
+                    }
+                }
+
+                let tmp_node = Rc::clone(node.borrow().next.get(&c).unwrap());
+                node = tmp_node;
+            }
+        }
+
+        let word: Vec<char> = s.chars().collect();
+        let n = s.len();
+        let mut dp = vec![false; n];
+
+        for i in 0..n {
+            if i > 0 && !dp[i - 1] {
+                continue;
+            }
+
+            let mut node = Rc::clone(&root);
+
+            let mut pos = i;
+            while pos < n && node.borrow().next.contains_key(&word[pos]) {
+                let next_node = Rc::clone(node.borrow().next.get(&word[pos]).unwrap());
+
+                dp[pos] = next_node.borrow().is_word || dp[pos];
+                pos += 1;
+                node = next_node;
+            }
+        }
+
+        dp[n - 1]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_139() {
+        assert!(Solution::word_break("leetcode".to_owned(), vec_string!("leet", "code")));
+        assert!(Solution::word_break("applepenapple".to_owned(), vec_string!("apple", "pen")));
+        assert!(!Solution::word_break("catsandog".to_owned(), vec_string!("cats", "cat", "sand", "and", "cat")));
+        assert!(Solution::word_break("aaaaaaa".to_owned(), vec_string!("aaa", "aaaa")));
+    }
+}