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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>& dictionary, string sentence) {
        Trie* trie = new Trie();
        for (int i = 0; i < dictionary.size(); ++i) {
            trie->insert(dictionary[i], i);
        }
        stringstream ss(sentence);
        string w;
        string ans;
        while (ss >> w) {
            int idx = trie->search(w);
            ans += (idx == -1 ? w : dictionary[idx]) + " ";
        }
        ans.pop_back();
        return ans;
    }
};

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type Trie struct {
    children [26]*Trie
    ref      int
}

func newTrie() *Trie {
    return &Trie{ref: -1}
}

func (this *Trie) insert(w string, i int) {
    node := this
    for _, c := range w {
        idx := c - 'a'
        if node.children[idx] == nil {
            node.children[idx] = newTrie()
        }
        node = node.children[idx]
    }
    node.ref = i
}

func (this *Trie) search(w string) int {
    node := this
    for _, c := range w {
        idx := c - 'a'
        if node.children[idx] == nil {
            return -1
        }
        node = node.children[idx]
        if node.ref != -1 {
            return node.ref
        }
    }
    return -1
}

func replaceWords(dictionary []string, sentence string) string {
    trie := newTrie()
    for i, w := range dictionary {
        trie.insert(w, i)
    }
    ans := strings.Builder{}
    for _, w := range strings.Split(sentence, " ") {
        if idx := trie.search(w); idx != -1 {
            ans.WriteString(dictionary[idx])
        } else {
            ans.WriteString(w)
        }
        ans.WriteByte(' ')
    }
    return ans.String()[:ans.Len()-1]
}

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class Trie {
    #children: Record<string, Trie> = {};
    #ref = -1;

    insert(w: string, i: number) {
        let node: Trie = this;
        for (const c of w) {
            node.#children[c] ??= new Trie();
            node = node.#children[c];
        }
        node.#ref = i;
    }

    search(w: string): number {
        let node: Trie = this;
        for (const c of w) {
            if (!node.#children[c]) {
                return -1;
            }
            node = node.#children[c];
            if (node.#ref !== -1) {
                return node.#ref;
            }
        }
        return -1;
    }
}

function replaceWords(dictionary: string[], sentence: string): string {
    const trie = new Trie();
    for (let i = 0; i < dictionary.length; i++) {
        trie.insert(dictionary[i], i);
    }
    return sentence
        .split(' ')
        .map(w => {
            const idx = trie.search(w);
            return idx !== -1 ? dictionary[idx] : w;
        })
        .join(' ');
}

Solution 2

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class Trie {
    private Trie[] children = new Trie[26];
    private int ref = -1;

    public void insert(String w, int i) {
        Trie node = this;
        for (int j = 0; j < w.length(); ++j) {
            int idx = w.charAt(j) - 'a';
            if (node.children[idx] == null) {
                node.children[idx] = new Trie();
            }
            node = node.children[idx];
        }
        node.ref = i;
    }

    public int search(String w) {
        Trie node = this;
        for (int j = 0; j < w.length(); ++j) {
            int idx = w.charAt(j) - 'a';
            if (node.children[idx] == null) {
                return -1;
            }
            node = node.children[idx];
            if (node.ref != -1) {
                return node.ref;
            }
        }
        return -1;
    }
}

class Solution {
    public String replaceWords(List<String> dictionary, String sentence) {
        Trie trie = new Trie();
        for (int i = 0; i < dictionary.size(); ++i) {
            trie.insert(dictionary.get(i), i);
        }
        List<String> ans = new ArrayList<>();
        for (String w : sentence.split("\\s")) {
            int idx = trie.search(w);
            ans.add(idx == -1 ? w : dictionary.get(idx));
        }
        return String.join(" ", ans);
    }
}

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function replaceWords(dictionary: string[], sentence: string): string {
    const words = sentence.split(' ');
    const trie: Trie = {};
    const TERMINAL_MARK = 'TERMINAL_MARK';

    for (const s of dictionary) {
        let t = trie;

        for (const ch of s) {
            t[ch] ??= {};
            t = t[ch] as Trie_;
        }
        t[TERMINAL_MARK] = TERMINAL_MARK;
    }

    for (let i = 0; i < words.length; i++) {
        const s = words[i];
        let t = trie;

        for (let j = 0; j < s.length; j++) {
            const ch = s[j];

            if (!t[ch]) break;

            if ((t[ch] as Trie_)[TERMINAL_MARK]) {
                words[i] = s.slice(0, j + 1);
                break;
            }
            t = t[ch] as Trie_;
        }
    }

    return words.join(' ');
}

// prettier-ignore
type Trie = { [key: string]: Trie} | string
type Trie_ = Exclude<Trie, string>;

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