Leetcode 274 - H-index

Note:

  • I lost 10 IQ while reading this description.
  • Two edge cases to think about:
    • When h === n. So if citations[i - 1] >= i, we need to include that citations[h] === undefined condition.
    • When h === 0. Return 0 as a base case.

Question:

Given an array of integers citations where citations[i] is the number of citations a researcher received for their ith paper, return compute the researcher’s h-index.

According to the definition of h-index on Wikipedia: A scientist has an index h if h of their n papers have at least h citations each, and the other n − h papers have no more than h citations each.

If there are several possible values for h, the maximum one is taken as the h-index.

Example:

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Input: citations = [3,0,6,1,5]
Output: 3
Explanation: [3,0,6,1,5] 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, their h-index is 3.

Code:

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/**
* @param {number[]} citations
* @return {number}
*/
var hIndex = function(citations) {
citations.sort((a, b) => b - a);
for (let i = citations.length; i >= 0; i--) {
if (i - 1 >= 0 && citations[i - 1] >= i && (citations[i] <= i || citations[i] === undefined)) return i;
}
return 0;
};