题目

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

Input Specification:

Each input file contains one test case. For each case, the first line contains two integers $N$ ( $\le 10^5$ ) 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 Specification:

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:

1
2
3
4

3 1
000007 James 85
000010 Amy 90
000001 Zoe 60

Sample Output 1:

1
2
3

000001 Zoe 60
000007 James 85
000010 Amy 90

Sample Input 2:

1
2
3
4
5

4 2
000007 James 85
000010 Amy 90
000001 Zoe 60
000002 James 98

Sample Output 2:

1
2
3
4

000010 Amy 90
000002 James 98
000007 James 85
000001 Zoe 60

Sample Input 3:

1
2
3
4
5

4 3
000007 James 85
000010 Amy 90
000001 Zoe 60
000002 James 9

Sample Output 3:

1
2
3
4

000002 James 9
000001 Zoe 60
000007 James 85
000010 Amy 90

鸣谢用户 wangzhj 补充数据！

思路

应该也是很基本的排序。三种排序选项，后两个还有二级排序。也没有什么特殊的处理，所以很简单。

代码

Github最新代码，欢迎交流

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#include <stdio.h>
#include <string.h>
#include <stdlib.h>

typedef struct {
	int ID;
	char name[9];
	int grade;
} Student, *pStudent;

/* increasing by ID */
int cmp1(const void *a, const void *b)
{
	pStudent s1 = *(pStudent*)a, s2 = *(pStudent*)b;
	return s1->ID - s2->ID;
}

/* non decreasing by name, then increasing by ID */
int cmp2(const void *a, const void *b)
{
	pStudent s1 = *(pStudent*)a, s2 = *(pStudent*)b;
	if (strcmp(s1->name, s2->name))
		return strcmp(s1->name, s2->name);
	else
		return s1->ID - s2->ID;
}

/* non decreasing by grade, then increasing by ID */
int cmp3(const void *a, const void *b)
{
	pStudent s1 = *(pStudent*)a, s2 = *(pStudent*)b;
	if (s1->grade - s2->grade)
		return s1->grade - s2->grade;
	else
		return s1->ID - s2->ID;
}

int main()
{
	int N, C;
	Student buffer[100000] = {0};
	pStudent students[100000] = {0}, *s = students;

	scanf("%d %d", &N, &C);
	for (int i = 0; i < N; i++, s++) {
		/* use a new struct buffer */
		*s = buffer + i;
		scanf("%d %s %d", &(*s)->ID, (*s)->name, &(*s)->grade);
	}

	if (C == 1)  /* increasing ID */
		qsort(students, N, sizeof(pStudent), cmp1);
	else if (C == 2)  /* non-decreasing name */
		qsort(students, N, sizeof(pStudent), cmp2);
	else  /* C == 3, non-decreasing grade */
		qsort(students, N, sizeof(pStudent), cmp3);

	for (int i = 0; i < N; i++)
		printf("%06d %s %d\n", students[i]->ID,
							   students[i]->name,
							   students[i]->grade);

	return 0;
}