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648. Replace Words

Description

In English, we have a concept called root, which can be followed by some other word to form another longer word - let's call this word derivative. For example, when the root "help" is followed by the word "ful", we can form a derivative "helpful".

Given a dictionary consisting of many roots and a sentence consisting of words separated by spaces, replace all the derivatives in the sentence with the root forming it. If a derivative can be replaced by more than one root, replace it with the root that has the shortest length.

Return the sentence after the replacement.

 

Example 1:

Input: dictionary = ["cat","bat","rat"], sentence = "the cattle was rattled by the battery"
Output: "the cat was rat by the bat"

Example 2:

Input: dictionary = ["a","b","c"], sentence = "aadsfasf absbs bbab cadsfafs"
Output: "a a b c"

 

Constraints:

  • 1 <= dictionary.length <= 1000
  • 1 <= dictionary[i].length <= 100
  • dictionary[i] consists of only lower-case letters.
  • 1 <= sentence.length <= 106
  • sentence consists of only lower-case letters and spaces.
  • The number of words in sentence is in the range [1, 1000]
  • The length of each word in sentence is in the range [1, 1000]
  • Every two consecutive words in sentence will be separated by exactly one space.
  • sentence does not have leading or trailing spaces.

Solutions

Solution 1

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class Trie:
    def __init__(self):
        self.children: List[Trie | None] = [None] * 26
        self.ref: int = -1

    def insert(self, w: str, i: int):
        node = self
        for c in w:
            idx = ord(c) - ord("a")
            if node.children[idx] is None:
                node.children[idx] = Trie()
            node = node.children[idx]
        node.ref = i

    def search(self, w: str) -> int:
        node = self
        for c in w:
            idx = ord(c) - ord("a")
            if node.children[idx] is None:
                return -1
            node = node.children[idx]
            if node.ref != -1:
                return node.ref
        return -1


class Solution:
    def replaceWords(self, dictionary: List[str], sentence: str) -> str:
        trie = Trie()
        for i, w in enumerate(dictionary):
            trie.insert(w, i)
        ans = []
        for w in sentence.split():
            idx = trie.search(w)
            ans.append(dictionary[idx] if idx != -1 else w)
        return " ".join(ans)

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class Solution {
    public String replaceWords(List<String> dictionary, String sentence) {
        Set<String> s = new HashSet<>(dictionary);
        String[] words = sentence.split(" ");
        for (int i = 0; i < words.length; ++i) {
            String word = words[i];
            for (int j = 1; j <= word.length(); ++j) {
                String t = word.substring(0, j);
                if (s.contains(t)) {
                    words[i] = t;
                    break;
                }
            }
        }
        return String.join(" ", words);
    }
}

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class Trie {
private:
    Trie* children[26];
    int ref;

public:
    Trie()
        : ref(-1) {
        memset(children, 0, sizeof(children));
    }

    void insert(const string& w, int i) {
        Trie* node = this;
        for (auto& c : w) {
            int idx = c - 'a';
            if (!node->children[idx]) {
                node->children[idx] = new Trie();
            }
            node = node->children[idx];
        }
        node->ref = i;
    }

    int search(const string& w) {
        Trie* node = this;
        for (auto& c : w) {
            int idx = c - 'a';
            if (!node->children[idx]) {
                return -1;
            }
            node = node->children[idx];
            if (node->ref != -1) {
                return node->ref;
            }
        }
        return -1;
    }
};

class Solution {
public:
    string replaceWords(vector<string>