zoukankan      html  css  js  c++  java
  • 274. 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 least h citations each, and the other N − h papers have no more than h citations each."

    Example:

    Input: citations = [3,0,6,1,5]
    Output: 3 
    Explanation: [3,0,6,1,5] 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, her h-index is 3.

    Note: If there are several possible values for h, the maximum one is taken as the h-index.

    solution: (reference: https://leetcode.com/problems/h-index/discuss/70768/Java-bucket-sort-O(n)-solution-with-detail-explanation)

    用bucket sort,假设共有n 篇paper,那么我们维持n + 1 个bucket,bucket[i] 表示 citation 为 i 的paper数量,buckec[n] 表示 citation > n 的 paper数量。

    然后,为找到最大的h-index,从右往左遍历bucket[i] 并累计paper 数目总量 count,如果count >= i,说明当前有 i (count = i) 篇 paper 的 citation 都大于 i ,那么 i 就是 greatest h-index. (剩下的 paper 每篇 citation 数肯定都小于 i)

    time = O(n), space = O(n)

    class Solution {
        public int hIndex(int[] citations) {
            int n = citations.length;
            int[] bucket = new int[n + 1];
            for(int citation : citations) {
                if(citation >= n) {
                    bucket[n]++;
                } else {
                    bucket[citation]++;
                }
            }
            
            int count = 0;
            for(int i = n; i >= 0; i--) {
                count += bucket[i];
                if(count >= i) {
                    return i;
                }
            }
            return 0;
        }
    }
  • 相关阅读:
    夜生活
    LOST
    TMD
    玩AJAX要先知道这些
    水漫金陵
    家装
    JAVA里面的小名堂
    朋友值多少钱
    猪八戒
    冬枣
  • 原文地址:https://www.cnblogs.com/fatttcat/p/13515551.html
Copyright © 2011-2022 走看看