题解 | #在有序但是含有空的数组中查找字符串#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    //二分查找
    public static int getIndex(String[] strs, String str) {
        if (strs == null || strs.length == 0 || str == null) {
            return -1;
        }
        int res = -1; //返回的位置
        int left = 0;
        int right = strs.length - 1;
        int mid = 0;
        int i = 0;
        while (left <= right) {
            mid = (left + right) / 2;
            //1、找到了
            if (strs[mid] != null && strs[mid].equals(str)) {
                res = mid;
                right = mid - 1;
            } else if (strs[mid] != null) {//2、没找到,mid处不为null
                if (strs[mid].compareTo(str) < 0) {//2.1 找右半区
                    left = mid +1;
                } else {            //2.2 找左半区
                    right = mid - 1;
                }
            }else{//3. mid处为null
                i=mid;
                //找不等于null的位置
                while (strs[i]==null&&--i>=left)
                    ;
                if(i<left||strs[i].compareTo(str)<0){
                    left=mid+1;
                }else{
                    res=strs[i].equals(str)?i:res;
                    right=i-1;
                }
            }
        }
        return res;

    }

    public static void main(String[] args) throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(bf.readLine());
        String str = bf.readLine();
        String[] data = new String[n];
        for (int i = 0; i < n; i++) {
            data[i] = bf.readLine();
            data[i] = data[i].equals("0") ? null : data[i];
        }
        bf.close();
        System.out.println(getIndex(data, str));
    }
}