课堂练习

思路：水王的发帖数超过了总帖数的一半，水王的帖子要比其他所有人的帖子加起来还要多。比较相邻两个发帖ID，若不相同，把两个帖子全部删除；若相同，删除一个，在这之后再继续比较。到最后剩下的就是水王的id。

package test2;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;




public class ShuiWang {
    public static void main(String[] args) throws IOException {
        find();
    }

    public static void find() throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("sw.txt"));
        String s,s1 = null,s2 = null,shuiwang = null;
        int i=1;
        while((s = br.readLine()) != null) {
            s1 = s;
            if(s2 == null) {
                s2 = br.readLine();
            }
            System.out.println("------------------------------------------");
            System.out.println("第" + i++ + "次比较");
            System.out.println("s1:" + s1);
            System.out.println("s2:" + s2);
            if(s2 != null) { 
                if(s1.compareTo(s2) != 0) 
                    s2 = null;
                else                      
                    shuiwang = s2;
            }else {
                shuiwang = s1;
            }
            System.out.println("记录id:" + shuiwang);
        }
        if(shuiwang == null)
            shuiwang = s2;
        System.out.println("\n水王id为:" + shuiwang);
        br.close();
    }

}