题目介绍

题解

h指数不一定都满足citations[mid] == n - mid，例如[0,1,4,5,6]的h指数是3。

题目说了用对数时间复杂度来实现，说明一定是用二分法，草纸上推导一下即可得出以下代码。

class Solution {
    public int hIndex(int[] citations) {
        int l = 0, n = citations.length, r = n - 1,mid = 0;
        while(l <= r){
            mid = (l + r)/2;
            if(citations[mid] == n - mid){
                return n - mid;
            }else if(citations[mid] > n - mid){
                r = mid - 1;
            }else{
                l = mid + 1;
            }
        }
        return n - l;
    }
}