UVA 11462-Age sort

#include <iostream>
#include <cstdio>
#include <cstring>
#include <fstream>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <algorithm>
#include <set>
#include <map>
#include <list>
#include <stack>
#include <queue>
#include <iterator>
#include <vector>

using namespace std;

#define LL long long
#define INF 0x3f3f3f3f
#define MOD 1000000007
#define MAXN 10000010
#define MAXM 1000010

const int MAXN = 2000000+5;
int a[MAXN];

// 方法一：快速排序

int cmp(const void *a, const void *b)
{
return *(int *)a - *(int *)b;
}

void qsort(int b[], int l, int r)
{
int i, j, x;
i = l;
j = r;
x = b[i];

while(i != j)
{
while(b[j]>x&&j>i)
j--;
if(i < j)
{
b[i] = b[j];
i++;
}
while(b[i]<x&&j>i)
i++;
if(i < j)
{
b[j] = b[i];
j--;
}
}

b[i] = x;
qsort(b, l, j-1);
qsort(b, i+1, r);
}

int main()
{
int n;
while(scanf("%d", &n)==1&&n)
{
int i;
for(i = 0; i < n; i++ )
scanf("%d", &a[i]);

qsort(a, n, sizeof(a[0]), cmp);

for(i = 0; i < n; i++ )
{
if(i != 0)
printf(" ");
printf("%d", a[i]);
}

printf("\n");
}

return 0;
}

//方法二：计数排序

int main()
{
int n;
int x;
int i, j;
while(scanf("%d", &n)==1&&n)
{
int flag = 0;
memset(a, 0, sizeof(a));
for(i = 1; i <= n; i++ )
{
scanf("%d", &x);
a[x]++;
}
for(i = 1; i <= 100; i++ )  //年龄：1-100岁
for(j = 1; j <= a[i]; j++ ) //每个年龄的人数（年龄从1岁开始）
{
if(flag)
printf(" ");
flag = 1;
printf("%d", i);
}
printf("\n");
}
return 0;
}