Last updated on January 5th, 2025 at 01:11 am

Here, we see a H-Index LeetCode Solution. This Leetcode problem is solved using different approaches in many programming languages, such as C++, Java, JavaScript, Python, etc.

List of all LeetCode Solution

Topics

Hash-Table, Sort

Companies

Bloomberg, Facebook, Google

Level of Question

Medium

H-Index LeetCode Solution

1. Problem Statement

Given an array of integers citations where citations[i] is the number of citations a researcher received for their i^th 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.

Example 1:
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.

Example 2:
Input: citations = [1,3,1]
Output: 1

2. Coding Pattern Used in Solution

The coding pattern used in these implementations is Counting/Sorting-Based Search or Modified Binary Search (depending on the implementation).

3. Code Implementation in Different Languages

3.1 H-Index C++

class Solution {
public:
    int hIndex(vector<int>& citations) {
        return hIndexBruteForce(citations);        
    }
    
    int hIndexBruteForce(vector<int>& c) {
        sort(c.begin(), c.end());
        int n = c.size();
        int maxi = 0;
        for(int i = 0; i < n; i++) {
            if(c[i] >= n - i) {
                maxi = max(maxi, n - i);
            }
        }
        return maxi;
    }
};

3.2 H-Index Java

class Solution {
    public int hIndex(int[] citations) {
        int low=0 , high = citations.length;
        while(low < high){
            int mid = (low+high+1)/2;
            int cnt=0;
            for(int i=0 ; i<citations.length ; i++) if(citations[i] >= mid) cnt++;
            if(cnt >= mid) low = mid;
            else high = high=mid-1;
        }
        return low;        
    }
}

3.3 H-Index JavaScript

var hIndex = function(citations) {
    citations.sort((a,b)=>b-a)
    let i=0
    while(citations[i]>i) i++ 
    return i    
};

3.4 H-Index Python

class Solution(object):
    def hIndex(self, citations):
        n = len(citations)
        papers = [0] * (n + 1)
        for c in citations:
            papers[min(n, c)] += 1
        i = n
        s = papers[n]
        while i > s:
            i -= 1
            s += papers[i]
        return i

4. Time and Space Complexity

	Time Complexity	Space Complexity
C++	O(n log n)	O(1)
Java	O(n log n)	O(1)
JavaScript	O(n log n)	O(1)
Python	O(n)	O(n)