O(n) Easy Understand Solution


  • 0
    A
    class Solution {
    public:
        int hIndex(vector<int>& citations) {
            int n = citations.size();
            vector<int> tbl = vector<int>(n+1, 0);
            for (int i = 0; i < n; i++) {
                int tmp = citations[i];
                if (tmp >= n) tbl[n]++;
                else tbl[tmp]++;
            }
            int sum = 0;
            for (int i = n; i >= 0; i--) {
                sum += tbl[i];
                if (sum >= i) return i;
            }
            return -1;
        }
    };

  • 0
    S

    Hi,

    I came across a situation: given citations = [3, 1, 7, 8, 9]. What will be the answer be?

    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."

    When h=3, the definition will be "A scientist has index 3 if 3 of his/her 5 papers have at least 3 citations each, and the other 2 papers have no more than 3 citations each." Obviously wrong....

    When h=4, the definition will be "A scientist has index 4 if 4 of his/her 5 papers have at least 4 citations each, and the other 1 papers have no more than 4 citations each." Obviously wrong....

    When h=2, the definition will be "A scientist has index 2 if 2 of his/her 5 papers have at least 2 citations each, and the other 3 papers have no more than 3 citations each." Obviously wrong....


  • 0
    A

    Hello,

    h = 3 is correct. At first, I was as confused as you were.

    In fact, that is trick. 7, 8, 9 are at least 3, whereas 1, 3 are no more than 3.


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