#yyds干货盘点# LeetCode程序员面试金典：稀疏数组搜索

题目：

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

代码实现：

class Solution {
  public int findString(String[] words, String s) {
    int l = 0, r = words.length - 1;
    while (l <= r) {
      int mid = l + (r - l) / 2;
      // 如果mid指向空字符串，则将右指针(r)向左移动一个位置
      if (words[mid].equals("")) {
        // 移动右指针(r)之前先判断是否指向目标字符串，防止错过目标字符串
        if (words[r].equals(s)) return r;
        r--;
      } else if (words[mid].equals(s)) return mid;
      else if (words[mid].compareTo(s) > 0) r = mid - 1;
      else l = mid + 1;
    }
    return -1;
  }
}