Problem: https://leetcode.com/problems/h-index/
Given an array of citations (each citation is a non-negative integer) of a researcher, write a function to compute the researcher's h-index.
According to the definition of h-index on Wikipedia: "A scientist has index h if h of his/her N papers have at least h citations each, and the other N − h papers have no more than h citations each."
For example, given citations = [3, 0, 6, 1, 5]
, which means the researcher has 5
papers in total and each of them had received 3, 0, 6, 1, 5
citations respectively. Since the researcher has 3
papers with at least 3
citations each and the remaining two with no more than 3
citations each, his h-index is 3
.
Thought:
have an extra space to note bucket[i] papers have i citation, when n, bucket[n] = times more than n
Reference: https://leetcode.com/discuss/93819/java-bucket-sort-o-n-solution-with-detail-explanation
Code C++:
class Solution { public: int hIndex(vector<int>& citations) { int n = citations.size(); int* bucket = new int[n+1]; for (int i = 0; i <= n; i++){ bucket[i] = 0; } for (int i = 0; i < citations.size(); i++) { if (citations[i] > n) { bucket[n]++; } else { bucket[citations[i]]++; } } int count = 0; for (int i = n; n >= 0; i--) { count += bucket[i]; if (count >= i) { return i; } } return 0; } };