Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm?

思路

接上一题，按顺序排列，方法更为简洁。一趟遍历即可解决。

P.S. 更可以用二分查找法。

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class Solution {
public:
    int hIndex(vector<int>& citations) {
        int result = 0;
        if(citations.size()>0){
            for (int i = citations.size() - 1; i >= 0; i--){
                int count = citations.size() - i;
                if(citations[i] >= count) {
                    result = max(count, result);
                }
            }
            if(result > 0) return result;
            else{
                int size = citations.size();
                int start = citations[0];
                result = min(size, start);
                return result;
            }
        }
        else return 0;
    }
};