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2399. Check Distances Between Same Letters 👍

  • Time: $O(n)$
  • Space: $O(26) = O(1)$
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class Solution {
 public:
  bool checkDistances(string s, vector<int>& distance) {
    vector<int> firstSeenIndex(26, -1);

    for (int i = 0; i < s.length(); ++i) {
      const int j = s[i] - 'a';
      int& prevIndex = firstSeenIndex[j];
      if (prevIndex != -1 && i - prevIndex - 1 != distance[j])
        return false;
      prevIndex = i;
    }

    return true;
  }
};

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class Solution {
  public boolean checkDistances(String s, int[] distance) {
    int[] firstSeenIndex = new int[26];
    Arrays.fill(firstSeenIndex, -1);

    for (int i = 0; i < s.length(); ++i) {
      final int j = s.charAt(i) - 'a';
      final int prevIndex = firstSeenIndex[j];
      if (prevIndex != -1 && i - prevIndex - 1 != distance[j])
        return false;
      firstSeenIndex[j] = i;
    }

    return true;
  }
}

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class Solution:
  def checkDistances(self, s: str, distance: list[int]) -> bool:
    firstSeenIndex = [-1] * 26

    for i, c in enumerate(s):
      j = string.ascii_lowercase.index(c)
      prevIndex = firstSeenIndex[j]
      if prevIndex != -1 and i - prevIndex - 1 != distance[j]:
        return False
      firstSeenIndex[j] = i

    return True