1012 The Best Rank (25 分) java

题意：

抓住一点，按照A—>C—>M—>E的顺序取每门成绩的最高排名，因为每个学生的成绩是鼓励式的，所以允许有并列。如果只有A，B两个学生，且A和B的Average都是90，但是A的C语言成绩比B的C语言成绩高，B仍然输出 1  A。

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解题思路：

用4个ArrayList<Student>存储学生排名，分别按照A，C，M，E升序排列。同时用一个Map来存储<Student.id,  Student.rank[]>键值对，在代码里面对应<String, int[]>，前面代表学生ID，后面顺序存储学生的A，C，M，E四门成绩的排名。在处理排名数组的时候注意可以并列，用 lastIndex和 lastGrade两个变量可以解决这个问题，而不是简单的对应遍历下标 i（坑）。最后输出的时候遍历对应学生ID的rank[]数组，输出最小的就行。

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import java.util.Comparator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Map;
import java.util.HashMap;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Map.Entry;
import java.util.Set;
public class Main {
	public static void main(String[] args) throws IOException{
		
		BufferedReader rd = new BufferedReader(new InputStreamReader(System.in));
		String nm[] = rd.readLine().split(" ");
		int N = Integer.parseInt(nm[0]);
		int M = Integer.parseInt(nm[1]);
		ArrayList<Student> aList = new ArrayList<>();
		ArrayList<Student> cList = new ArrayList<>();
		ArrayList<Student> mList = new ArrayList<>();
		ArrayList<Student> eList = new ArrayList<>();
		
		Map<String, int[]> map = new HashMap<>();
		for(int i=0; i<N; i++) {
			String str[] = rd.readLine().split(" ");
			String id = str[0];
			int c = Integer.parseInt(str[1]);
			int m = Integer.parseInt(str[2]);
			int e = Integer.parseInt(str[3]);
			Student stu = new Student(id, c, m, e);
			aList.add(stu);
			cList.add(stu);
			mList.add(stu);
			eList.add(stu);
			map.put(id, new int[4]);
		}
		
		Collections.sort(aList, new Comparator<Student>(){
			@Override
			public int compare(Student o1, Student o2) {
				return o2.avg - o1.avg ;
			}
		});
//		System.out.println("\n-------------");
//		for(Student e: aList)
//			System.out.print(e.avg + " ");
//		System.out.println("\n-------------");
		
		int lastIndex = 0;
		int lastGrade = aList.get(lastIndex).avg;
		for(int i=0; i<aList.size(); i++) {
			int temp = aList.get(i).avg;
			if(lastGrade != temp) {
				lastIndex = i;
			}
			map.get(aList.get(i).id)[0] = lastIndex+1;
			lastGrade = temp;
		}
			
		
		
		Collections.sort(cList, new Comparator<Student>(){
			@Override
			public int compare(Student o1, Student o2) {
				return o2.c - o1.c;
			}
		});
		
		lastIndex = 0;
		lastGrade = cList.get(lastIndex).c;
		for(int i=0; i<cList.size(); i++) {
			int temp = cList.get(i).c;
			if(lastGrade != temp)
				lastIndex = i;
			map.get(cList.get(i).id)[1] = lastIndex+1;
			lastGrade = temp;
		}
		
		Collections.sort(mList, new Comparator<Student>(){
			@Override
			public int compare(Student o1, Student o2) {
				return o2.m - o1.m;
			}
		});
		lastIndex = 0;
		lastGrade = mList.get(lastIndex).m;
		for(int i=0; i<mList.size(); i++) {
			int temp = mList.get(i).m;
			if(lastGrade != temp)
				lastIndex = i;
			map.get(mList.get(i).id)[2] = lastIndex+1;
			lastGrade = temp;
		}
		
		Collections.sort(eList, new Comparator<Student>(){
			@Override
			public int compare(Student o1, Student o2) {
				return o2.e - o1.e;
			}
		});
		lastIndex = 0;
		lastGrade = eList.get(lastIndex).e;
		for(int i=0; i<eList.size(); i++) {
			int temp = eList.get(i).e;
			if(lastGrade != temp)
				lastIndex = i;
			map.get(eList.get(i).id)[3] = lastIndex+1;
			lastGrade = temp;
		}
		
		
//		Set<Entry<String, int[]>> entrySet = map.entrySet();
//		for(Entry<String, int[]> e: entrySet) {
//			System.out.print(e.getKey());
//			int temp[] = e.getValue();
//			for(int i=0; i<temp.length; i++)
//				System.out.print(" " + temp[i]);
//			System.out.println();
//		}
//		
		
		for(int i=0; i<M; i++) {
			String check = rd.readLine();
			if(!map.containsKey(check)) 
				System.out.println("N/A");
			else {
				int rank[] = map.get(check);
				int index = 0;
				int bestRank = rank[0];
				for(int j=1; j<rank.length; j++) {
					if(rank[j] < bestRank) {
						bestRank = rank[j];
						index = j;
					}
				}
				if(index == 0) System.out.printf("%d A\n", bestRank);
				if(index == 1) System.out.printf("%d C\n", bestRank);
				if(index == 2) System.out.printf("%d M\n", bestRank);
				if(index == 3) System.out.printf("%d E\n", bestRank);
			}
		}
		
	}
	static class Student{
		String id;
		int c;
		int m;
		int e;
		int avg;
		public Student(String id, int c, int m, int e){
			this.id = id;
			this.c = c;
			this.m = m;
			this.e = e;
			this.avg = (c+m+e) / 3;
		}
	}
}

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写在后面：

这题捣鼓了快2个小时，觉得思路是没问题的，就是java太慢了=.=，3和4一直不通过。但是C和C++又太菜，改天再回来补一补吧。。。。。。