[LeetCode][JavaScript]H-Index

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.

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

Hint:

1. An easy approach is to sort the array first.
2. What are the possible values of h-index?
3. A faster approach is to use extra space.

https://leetcode.com/problems/h-index/

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h因子，万能的百度百科剧透了解法...

h代表“高引用次数”（high citations），一名科研人员的h指数是指他至多有h篇论文分别被引用了至少h次。

要确定一个人的h指数非常容易，到SCI网站，查出某个人发表的所有SCI论文，让其按被引次数从高到低排列，往下核对，直到某篇论文的序号大于该论文被引次数，那个序号减去1就是h指数。

 H-Index II: http://www.cnblogs.com/Liok3187/p/4782660.html

/**
 * @param {number[]} citations
 * @return {number}
 */
var hIndex = function(citations) {
    citations = citations.sort(sorting);
    var i = 0;
    while(i + 1 <= citations[i]){
        i++;
    }
    return i;


    function sorting(a, b){
        return b - a;
    }
};