# [leetcode] H-Index

H-Index

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 leasth citations each, and the other N − h papers have no more thanh 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.

Bucket sort

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

o(nlogn) approach

```class Solution {
public:
int hIndex(vector<int>& citations) {
int ans = 0;
if(citations.size() == 0) return 0;
sort(citations.begin(), citations.end());
for(int i = citations.size() - 1; i >= 0; i--){
int v = citations[i];
if(v <= citations.size() - i - 1){
return citations.size() - i - 1;
}
}
return citations.size();
}
};``` This site uses Akismet to reduce spam. Learn how your comment data is processed.