H-Index

Problem statement

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 1:

Input: citations = [3,0,6,1,5]Output: 3Explanation: [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

Constraints:

• n == citations.length
• 1 <= n <= 5000
• 0 <= citations[i] <= 1000

My solution

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

// var hIndex = function(citations) {
//     let len = citations.length;
//     let hIndex = 0;
//     let dp = Array.from({
//         length: len + 1
//     }, () => 0)
    
//     for (const n of citations) {
//         if (n >= len) {
//             dp[len]++
//         } else {
//             dp[n]++
//         }
//     }
    
//     for (let i = 0; i <= dp.length; i++) {
//         if (!dp[i]) {
//             continue;
//         }
        
//         hIndex = Math.max(hIndex, Math.min(len, i))
//         len -= dp[i]
//     }
    
//     return hIndex;
// };