问题描述：
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
class Solution { public: int hIndex(vector<int>& citations) { if (citations.empty()) return 0; int len = citations.size(); qSort(citations, 0, len - 1); int i = 0; for (; i < len && citations[i] > i; i++); return i; } int partition(vector<int>& list, int low, int high) { int pivotkey = list[low]; while (low < high) { while (low < high && pivotkey >= list[high]) high--; list[low] = list[high]; while (low < high&&pivotkey <= list[low]) low++; list[high] = list[low]; } list[low] = pivotkey; return low; } void qSort(vector<int>& list, int low, int high) { if (list.empty()) return; if (low < high) { int part = partition(list, low, high); qSort(list, low, part - 1); qSort(list, part + 1, high); } } };
