去掉“using namespace std;”后程序仍能正常编译运行。

#include<iostream>

#include<cstring>

#include<cstdio>

#define N 500+10

using namespace std;

int a[N], n;

int main() {

    cin >> n;

    for ( int i = 1; i <= n; i++) cin >> a[i];

    for ( int i = 1; i < n; i++)

        for ( int j = i+1; j <= n; j++) {

            int tmp = i;

            if(a[j] < a[tmp]) tmp = j;

            swap( a[i], a[tmp] );

        }

    for ( int i = 1; i <= n; i++) cout << a[i] << " ";

    cout << endl;

    return 0;

}