PAT 甲级 1025 PAT Ranking 排序

最新推荐文章于 2021-08-02 22:47:34 发布

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最新推荐文章于 2021-08-02 22:47:34 发布

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分类专栏：算法 PAT 文章标签：排序算法

本文链接：https://blog.youkuaiyun.com/qq_38939675/article/details/104802542

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本文介绍了一个编程能力测试(PAT)竞赛的排名系统实现方案。该系统由浙江大学计算机科学与技术学院组织，旨在同时处理多个地点的考试成绩，并即时合并生成最终排名。系统首先对每个考场的成绩进行排序，确定考场内的排名，然后对所有考生的成绩进行全局排序，生成最终的总排名。

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Programming Ability Test (PAT) is organized by the College of Computer Science and Technology of Zhejiang University. Each test is supposed to run simultaneously in several places, and the ranklists will be merged immediately after the test. Now it is your job to write a program to correctly merge all the ranklists and generate the final rank.

Input Specification:

Each input file contains one test case. For each case, the first line contains a positive number N (≤100), the number of test locations. Then N ranklists follow, each starts with a line containing a positive integer K (≤300), the number of testees, and then K lines containing the registration number (a 13-digit number) and the total score of each testee. All the numbers in a line are separated by a space.

Output Specification:

For each test case, first print in one line the total number of testees. Then print the final ranklist in the following format:

registration_number final_rank location_number local_rank

The locations are numbered from 1 to N. The output must be sorted in nondecreasing order of the final ranks. The testees with the same score must have the same rank, and the output must be sorted in nondecreasing order of their registration numbers.

Sample Input:

2
5
1234567890001 95
1234567890005 100
1234567890003 95
1234567890002 77
1234567890004 85
4
1234567890013 65
1234567890011 25
1234567890014 100
1234567890012 85

Sample Output:

9
1234567890005 1 1 1
1234567890014 1 2 1
1234567890001 3 1 2
1234567890003 3 1 2
1234567890004 5 1 4
1234567890012 5 2 2
1234567890002 7 1 5
1234567890013 8 2 3
1234567890011 9 2 4

创建比较器实现Comparator接口

先对各考场考生分别排序得到考生的考场内排名，再对所有考生排序得到总排名。


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

class Student{
	String id;
	int localRank,grade,locationNo;
}
class Cmp implements Comparator<Student>{

	@Override
	public int compare(Student o1, Student o2) {
		if(o1.grade!=o2.grade)
			return o1.grade>o2.grade?-1:1;//降序排序
//			return o2.grade-o1.grade;
		return o1.id.compareTo(o2.id);//升序排序
	}
	
}
public class Main {
	
	
    public static void main(String[] args) throws IOException {
    	BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));

//    	Scanner sc=new Scanner(System.in);

    	int N=Integer.valueOf(reader.readLine()),num=0;//num记录学生个数
    	String[] line=null;
    	Student[] stu=new Student[30001];
    	
    	for(int i=1;i<=N;i++) {
    		int K=Integer.valueOf(reader.readLine());
    		for(int j=0;j<K;j++) {
    	    	line=reader.readLine().split(" ");
    			stu[num]=new Student();
    			stu[num].id=line[0];
    			stu[num].grade=Integer.valueOf(line[1]);
    			stu[num].locationNo=i;
    			num++;//考生数+1
    		}
    		//考场内排序（左闭右开）
    		Arrays.sort(stu,num-K,num,new Cmp());
    		//记录考场内排名
    		stu[num-K].localRank=1;
    		for(int j=num-K+1;j<num;j++) {
    			if(stu[j].grade!=stu[j-1].grade)//若与前一位不同分则排名为下标
    				stu[j].localRank=j-(num-K)+1;
    			else//若与前一位同分则排名不变
    				stu[j].localRank=stu[j-1].localRank;
    		}
    	}
    	
    	System.out.println(num);
    	//所有考生排序
    	Arrays.sort(stu,0,num,new Cmp());
    	//计算总排名
    	int r=1;
    	for(int i=0;i<num;i++) {
    		if(i>0&&stu[i].grade!=stu[i-1].grade)
    			r=i+1;//排名更新
    		System.out.println(stu[i].id+" "+r+" "+stu[i].locationNo+" "+stu[i].localRank);
    	}
    }
}