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2416. Sum of Prefix Scores of Strings 👍

  • Time: $O(\Sigma |\texttt{words[i]}|)$
  • Space: $O(\Sigma |\texttt{words[i]}|)$
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struct TrieNode {
  vector<shared_ptr<TrieNode>> children;
  int count = 0;
  TrieNode() : children(26) {}
};

class Solution {
 public:
  vector<int> sumPrefixScores(vector<string>& words) {
    vector<int> ans;

    for (const string& word : words)
      insert(word);

    for (const string& word : words)
      ans.push_back(getScore(word));

    return ans;
  }

 private:
  shared_ptr<TrieNode> root = make_shared<TrieNode>();

  void insert(const string& word) {
    shared_ptr<TrieNode> node = root;
    for (const char c : word) {
      const int i = c - 'a';
      if (node->children[i] == nullptr)
        node->children[i] = make_shared<TrieNode>();
      node = node->children[i];
      ++node->count;
    }
  }

  int getScore(const string& word) {
    shared_ptr<TrieNode> node = root;
    int score = 0;
    for (const char c : word) {
      node = node->children[c - 'a'];
      score += node->count;
    }
    return score;
  }
};

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class TrieNode {
  public TrieNode[] children = new TrieNode[26];
  public int count = 0;
}

class Solution {
  public int[] sumPrefixScores(String[] words) {
    int[] ans = new int[words.length];

    for (final String word : words)
      insert(word);

    for (int i = 0; i < words.length; ++i)
      ans[i] = getScore(words[i]);

    return ans;
  }

  private TrieNode root = new TrieNode();

  private void insert(String word) {
    TrieNode node = root;
    for (final char c : word.toCharArray()) {
      final int i = c - 'a';
      if (node.children[i] == null)
        node.children[i] = new TrieNode();
      node = node.children[i];
      ++node.count;
    }
  }

  private int getScore(String word) {
    TrieNode node = root;
    int score = 0;
    for (final char c : word.toCharArray()) {
      node = node.children[c - 'a'];
      score += node.count;
    }
    return score;
  }
}

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class TrieNode:
  def __init__(self):
    self.children: dict[str, TrieNode] = {}
    self.count = 0


class Solution:
  def sumPrefixScores(self, words: list[str]) -> list[int]:
    root = TrieNode()

    def insert(word: str) -> None:
      node: TrieNode = root
      for c in word:
        node = node.children.setdefault(c, TrieNode())
        node.count += 1

    for word in words:
      insert(word)

    def getScore(word: str) -> int:
      node: TrieNode = root
      score = 0
      for c in word:
        node = node.children[c]
        score += node.count
      return score

    return [getScore(word) for word in words]