H index

gistfile1.txt

class Solution {
    /*
    public int hIndex(int[] citations) {
        Arrays.sort(citations);
        int res = citations.length;
        for(int i=0; i < citations.length; i++) {
            if( res > citations[i] ) {
                res--;
            } else {
                return res;
            }
        }
        return 0;
    }
    */
    // https://discuss.leetcode.com/topic/40765/java-bucket-sort-o-n-solution-with-detail-explanation
    public int hIndex(int[] citations) {
        int n = citations.length;
        int[] res = new int[n+1];
        for(int i=0; i < citations.length; i++) {
            if( citations[i] >= n) {
                res[n]++;
            } else {
                res[citations[i]]++;
            }
        }
        int count =0;
        for(int i=n; i >=0; i--) {
             count += res[i];
            if (count >= i) {
                return i;
            }
        }
        return 0;
    }
}