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LeetCode Solutions

274. H-Index

Time: $O(n)$

Space: $O(n)$

			


class Solution {
 public:
  int hIndex(vector<int>& citations) {
    const int n = citations.size();
    int accumulate = 0;
    vector<int> count(n + 1);

    for (const int citation : citations)
      ++count[min(citation, n)];

    // To find the largeset h-index, loop from back to front
    // I is the candidate h-index
    for (int i = n; i >= 0; --i) {
      accumulate += count[i];
      if (accumulate >= i)
        return i;
    }

    throw;
  }
};




			


class Solution {
  public int hIndex(int[] citations) {
    final int n = citations.length;
    int accumulate = 0;
    int[] count = new int[n + 1];

    for (final int citation : citations)
      ++count[Math.min(citation, n)];

    // To find the largeset h-index, loop from back to front
    // I is the candidate h-index
    for (int i = n; i >= 0; --i) {
      accumulate += count[i];
      if (accumulate >= i)
        return i;
    }

    throw new IllegalArgumentException();
  }
}




			


class Solution:
  def hIndex(self, citations: List[int]) -> int:
    n = len(citations)
    accumulate = 0
    count = [0] * (n + 1)

    for citation in citations:
      count[min(citation, n)] += 1

    # To find the largeset h-index, loop from back to front
    # I is the candidate h-index
    for i, c in reversed(list(enumerate(count))):
      accumulate += c
      if accumulate >= i:
        return i