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Solution.java
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Solution.java
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/**
* Time : O(N) ; Space: O(N)
* @tag : Hash Table; Sort
* @by : Steven Cooks
* @date: Sep 21, 2015
***************************************************************************
* Description:
*
* 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. *
*
***************************************************************************
* {@link https://leetcode.com/problems/h-index/ }
*/
package _274_HIndex;
/** see test {@link _274_HIndex.SolutionTest } */
public class Solution {
public int hIndex(int[] nums) {
int n = nums.length;
int[] counts = new int[n + 1];
// count for each citations
for (int num : nums) {
if (num >= n) {
counts[n]++;
} else {
counts[num]++;
}
}
int sum = 0;
for (int i = n; i >= 0; i--) {
if (counts[i] + sum >= i) {
return i;
} else {
sum += counts[i];
}
}
return 0;
}
}