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.
類似於計數排序,略。
C++:
// Runtime: 4 ms
class Solution {
public:
int hIndex(vector& citations) {
int len = citations.size();
vector cnt(len + 1, 0);
for_each(citations.begin(), citations.end(),
[len, &cnt](int n){ n >= len ? cnt[len]++ : cnt[n]++; });
for (int i = len; i >= 0; i--)
{
cnt[i] = i == len ? cnt[i] : cnt[i] + cnt[i + 1];
if (cnt[i] >= i)
{
return i;
}
}
return 0;
}
};
Java:
// Runtime: 1 ms
public class Solution {
public int hIndex(int[] citations) {
int len = citations.length;
int cnt[] = new int[len + 1];
for (int c : citations) {
if (c >= len) {
cnt[len]++;
}
else {
cnt[c]++;
}
}
for (int i = len; i >= 0; i--) {
cnt[i] += i == len ? 0 : cnt[i + 1];
if (cnt[i] >= i) {
return i;
}
}
return 0;
}
}