题目

思路

• 二分查找，右边区间需要满足条件nums[i] >= h
• 寻找右边区间的左端点即可

• 注意处理边界情况

  代码

  class Solution {
  public:
    // 排序之后，右边区间满足了条件：nums[i] >= h
    int hIndex(vector<int>& citations) {
        int n = citations.size();
        int left = 0, right = n - 1;
        while (left < right) {
            int mid = (left + right) / 2;
            if (citations[mid] >= (n - 1) - mid + 1) {
                right = mid;
            } else {
                left = mid + 1;
            }
        }
        // 右边区间的左端点 == n - 1
        if (citations[left] == 0) {
            return 0;
        } else {
            return (n - 1) - left + 1;
        }
    }
  };