阅读理解

• 题意要找的就是nums[mid] >= len - mid的第一个点
• 即找右半段的左端点
• 模板一

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