反正写了是挺久了

import java.io.*;
public class Main{
    public static void main(String[] args) throws Exception {
        BufferedReader sc=new BufferedReader(new InputStreamReader(System.in));
        int T=Integer.parseInt(sc.readLine());
        while(T--!=0){
            long start=0;
            long end=0;
            for(int i=1;i<=1;i++){
            String s[]=sc.readLine().split(" ");
            String[] sdata=s[0].split(":");
            String[] edata=s[1].split(":");
            int data1=0;
            int hour1=Integer.parseInt(sdata[0]);
            int mouth1=Integer.parseInt(sdata[1]);
            int second1=Integer.parseInt(sdata[2]);
            int hour2=Integer.parseInt(edata[0]);
            int mouth2=Integer.parseInt(edata[1]);
            int second2=Integer.parseInt(edata[2]);


            data1+=hour1*60*60;
            data1+=mouth1*60;
            data1+=second1;
            int data2=0;

            data2+=hour2*60*60;
            data2+=mouth2*60;
            data2+=second2;
            int append=0;
            if(s.length>2) append=Integer.parseInt(s[2].substring(2,3));
            int day=60*60*24;
            long data=data2+(append*60*60*24)-data1;
            start=data;

            }
            for(int i=1;i<=1;i++){
            String s[]=sc.readLine().split(" ");
            String[] sdata=s[0].split(":");
            String[] edata=s[1].split(":");
            int data1=0;
            int hour1=Integer.parseInt(sdata[0]);
            int mouth1=Integer.parseInt(sdata[1]);
            int second1=Integer.parseInt(sdata[2]);
            int hour2=Integer.parseInt(edata[0]);
            int mouth2=Integer.parseInt(edata[1]);
            int second2=Integer.parseInt(edata[2]);


            data1+=hour1*60*60;
            data1+=mouth1*60;
            data1+=second1;
            int data2=0;

            data2+=hour2*60*60;
            data2+=mouth2*60;
            data2+=second2;
            int append=0;
            if(s.length>2) append=Integer.parseInt(s[2].substring(2,3));
            int day=60*60*24;
            long data=data2+(append*60*60*24)-data1;
            end=data;

            }
            long res=(end+start)/2;
            System.out.printf("%02d:%02d:%02d\n",res/3600,res%3600/60,res%60);
        }
    }
}

看了y总直播后的优化

import java.io.*;
public class Main {
    static BufferedReader sc=new BufferedReader(new InputStreamReader(System.in));
    public static void main(String[] args) throws Exception{

        int T=Integer.parseInt(sc.readLine());
        while(T--!=0){
            int time=(get_time()+get_time())/2;
            System.out.printf("%02d:%02d:%02d\n",time/3600,time%3600/60,time%60);
        }
    }
    static int get_time() throws Exception{
        String[] s=sc.readLine().split(" ");
        String[] stime=s[0].split(":");
        String[] etime=s[1].split(":");
        int d=0;
        if(s.length>2) d=Integer.parseInt(s[2].substring(2,3));
        int h1=Integer.parseInt(stime[0])*60*60;
        int m1=Integer.parseInt(stime[1])*60;
        int s1=Integer.parseInt(stime[2]);
        int h2=Integer.parseInt(etime[0])*60*60;
        int m2=Integer.parseInt(etime[1])*60;
        int s2=Integer.parseInt(etime[2]);

        return h2+m2+s2-h1-m1-s1+(d*24*60*60);
    }
}