274. H-Index.md

class Solution {
public:
    int hIndex(vector<int>& citations) {
        std::sort(citations.begin(), citations.end());
        int n = citations.size();
        for (int i = n - 1; i >= 0; --i) {
            if (citations[i] < n - i)
                return n - i - 1;
        }
        return n;
    }
};

class Solution {
public:
    int hIndex(vector<int>& nums) {
        int n = nums.size(), total = 0;
        vector<int> count(n + 1, 0);
        for (int i = 0; i < n; ++i) {
            if (nums[i] < n + 1)
                count[nums[i]]++;
            else
                count[n]++;
        }
        for (int i = n; i >= 0; --i) {
            if (count[i]) total += count[i];
            if (total >= i) return i;
        }
        return 0;
    }
};