joj2016: Sort the Students

 2016: Sort the Students

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Result	TIME Limit	MEMORY Limit	Run Times	AC Times	JUDGE
	3s	8192K	1417	539	Standard

Given the class numbers and the scores of a group of students, you are to write a program to sort the students first by class number in ascending order and then by score in descending order.

Input

The input contains only one test case. The first line of the input contains an integerN(N<=300), indicating the number of students you are to sort. From the second line of the input, there are N lines, each of which contains two integers A_i and B_i, indicating the class number and the score of the i^th student.

Output

The output should contain N lines exactly, which should be sorted first by class number in ascending order and then by score in descending order. Each line of the output should contain two integers A_j and B_j(separated by a space) of the student in position j after sorting.

There shoud be no other information or blank in the output. See the sample output below for more details.

Sample Input

5

2 90

2 89

1 65

3 95

2 95

Sample Output

1 65

2 95

2 90

2 89

3 95

 

Problem Source: 2nd JLU Programming Contest

 

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This problem is used for contest: 6 

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没考虑自己实现排序，直接调用qsort...

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 
 4 typedef struct st
 5 {
 6     int sid;
 7     int data;
 8 }ST, *PST;
 9 
10 int cmp(const void *x, const void *y)
11 {
12     PST a = (PST)x;
13     PST b = (PST)y;
14 
15     if (a->sid != b->sid)
16     {
17         return a->sid - b->sid;
18     }
19     else
20     {
21         return b->data-a->data;
22     }
23 }
24 
25 int main(void)
26 {
27     freopen("in.txt", "r", stdin);
28 
29     int n;
30     ST st[350];
31     PST pst = &st[0];
32 
33     scanf("%d", &n);
34 
35     for (int i=0; i<n; i++)
36     {
37         scanf("%d%d", &((pst+i)->sid), &((pst+i)->data));
38     }
39 
40     qsort(st, n, sizeof(st[0]), cmp);
41 
42     for (int i=0; i<n; i++)
43     {
44         printf("%d %d", ((pst+i)->sid), ((pst+i)->data));
45         printf("\n");
46     }
47 
48     return 0;
49 }