1028. List Sorting (25)

Excel can sort records according to any column. Now you are supposed to imitate this function.

Input

Each input file contains one test case. For each case, the first line contains two integers N (<=100000) and C, where N is the number of records and C is the column that you are supposed to sort the records with. Then N lines follow, each contains a record of a student. A student's record consists of his or her distinct ID (a 6-digit number), name (a string with no more than 8 characters without space), and grade (an integer between 0 and 100, inclusive).

Output

For each test case, output the sorting result in N lines. That is, if C = 1 then the records must be sorted in increasing order according to ID's; if C = 2 then the records must be sorted in non-decreasing order according to names; and if C = 3 then the records must be sorted in non-decreasing order according to grades. If there are several students who have the same name or grade, they must be sorted according to their ID's in increasing order.

Sample Input 1

3 1000007 James 85000010 Amy 90000001 Zoe 60

Sample Output 1

000001 Zoe 60000007 James 85000010 Amy 90

Sample Input 2

4 2000007 James 85000010 Amy 90000001 Zoe 60000002 James 98

Sample Output 2

000010 Amy 90000002 James 98000007 James 85000001 Zoe 60

Sample Input 3

4 3000007 James 85000010 Amy 90000001 Zoe 60000002 James 90

Sample Output 3

000001 Zoe 60000007 James 85000002 James 90
000010 Amy 90
最后一个点运行超时
import java.util.Arrays;import java.util.Comparator;import java.util.Scanner;class Student{int sid;String sname;int score;}class SortByNumber_1 implements Comparator<Student>{//1，学号升序public int compare(Student o1, Student o2) {return o1.sid - o2.sid;}}class SortByNumber_2 implements Comparator<Student>{//2，名字字母升序public int compare(Student o1, Student o2) {//如果字母相同，按学号升序if((o1.sname.charAt(0) - 48) == (o2.sname.charAt(0) - 48)){return o1.sid - o2.sid;}return (o1.sname.charAt(0) - 48) - (o2.sname.charAt(0) - 48);}}class SortByNumber_3 implements Comparator<Student>{//3，成绩升序public int compare(Student o1, Student o2) {//如果成绩相同，按学号升序if(o1.score == o2.score){return o1.sid - o2.sid;}return o1.score - o2.score;}}public class Main{public static void main(String[] args) {Scanner in = new Scanner(System.in);int sum = in.nextInt(),charge = in.nextInt();Student[] stu = new Student[sum];for ( int i = 0; i < sum; i++ ){stu[i] = new Student();stu[i].sid = in.nextInt();stu[i].sname = in.next();stu[i].score = in.nextInt();}switch (charge) {case 1:SortByNumber_1 sb_1 = new SortByNumber_1();Arrays.sort(stu,sb_1);break;case 2:SortByNumber_2 sb_2 = new SortByNumber_2();Arrays.sort(stu,sb_2);break;case 3:SortByNumber_3 sb_3 = new SortByNumber_3();Arrays.sort(stu,sb_3);break;}for ( int i = 0; i < sum; i++ ){System.out.printf("%06d",stu[i].sid);System.out.println(" "+stu[i].sname+" "+stu[i].score);}}}
升序：o1.sid-o2.sid
降序：o2.sid-o1.sid
注意：
for ( int i = 0; i < sum; i++ ){stu[i] = new Student();stu[i].sid = in.nextInt();stu[i].sname = in.next();stu[i].score = in.nextInt();}

stu[i] = new Student();
new数组的时候并没有实例化stu[i],如果不实例化stu[i],会空指针异常
参考：http://www.2cto.com/kf/201504/395324.html