문제

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

According to the definition of h-index on Wikipedia: The h-index is defined as the maximum value of h such that the given researcher has published at least h papers that have each been cited at least h times.

구현 전 예상 풀이

class Solution {
    public int hIndex(int[] citations) {
        ascending_sort(citations)
        total = citations.length
        max = 0
        
        for(i = 0; i < total; i++)
	        citation = citations[i]
        	count = total - i
        	if(count >= citation)
            	max = citation
                
        return max
    }
}

citations = [100] 에서 틀렸다.

구현 코드

class Solution {
    public int hIndex(int[] citations) {
        int total = citations.length;
        int max = 0;

        Arrays.sort(citations);

        for (int i = 0; i < total; i++) {
            int citation = citations[i];
            int count = total - i;

            int result = Math.min(count, citation);
            max = Math.max(max, result);
        }

        return max;
    }
}

논문 개수와, 인용 숫자중에서 적은 값을 선택하였다.

다른 사람 풀이

public int hIndex(int[] citations) {
    int n = citations.length;
    int[] buckets = new int[n+1];
    for(int c : citations) {
        if(c >= n) {
            buckets[n]++;
        } else {
            buckets[c]++;
        }
    }
    int count = 0;
    for(int i = n; i >= 0; i--) {
        count += buckets[i];
        if(count >= i) {
            return i;
        }
    }
    return 0;
}

정렬을 하지않고 푸는 방법도 있다.

274. H-Index
다른 사람 풀이 링크