稀疏数组搜索（leetcode）

题目链接：面试题 10.05. 稀疏数组搜索 - 力扣（LeetCode） (leetcode-cn.com)

题目描述：

稀疏数组搜索。有个排好序的字符串数组，其中散布着一些空字符串，编写一种方法，找出给定字符串的位置。

示例：

示例1:

 输入: words = ["at", "", "", "", "ball", "", "", "car", "", "","dad", "", ""], s = "ta"
 输出：-1
 说明: 不存在返回-1。
示例2:

 输入：words = ["at", "", "", "", "ball", "", "", "car", "", "","dad", "", ""], s = "ball"
 输出：4
提示:

words的长度在[1, 1000000]之间

题目分析：

使用极其标准的二分查找模板，再加上搜索mid时的线性查找得

源码：

#include<bits/stdc++.h>
#include<unordered_map>
using namespace std;
int main()
{
    vector<string>words = { "CitZMIXZKoFbxvOlaza", "hBlKXdKJfBD" };
    string s("hBlKXdKJfBD");

    int l = 0, r = words.size() - 1, mid;
    while (l <= r)
    {
        mid = (l + r) >> 1;
        while (words[mid] == "" && mid < r)//线性查找符合要求的mid值
        {
            mid++;
        }
        if (words[mid].compare(s) == 0)
        {
            r = mid;
            break;
        }
        if (mid == r )
        {
            r = mid - 1;
            continue;
        }
        if (words[mid].compare(s) < 0)
            l = mid + 1;
        else
            r = mid - 1;

    }
    cout << (words[r].compare(s) == 0 ? r : -1);
}
/*
    vector<string>words = { "at", "", "", "", "ball", "", "", "car", "", "","dad", "", "" };
    string s("ta");
    -1

        vector<string>words = { "E jgeVQIZI", "EMuBXhHEDpDOS", "HhYVhpQjIaEsZtHQKy", "IOBAEIbBnjO", "MyHjLicHnzyrvRxvtw", "WYt DPvcv", "c" };
    string s("EMuBXhHEDpDOS");
    1
*/