贴上代码

#include<iostream>

#include "string.h"

using namespace std;

bool N[1001];

int main()

{

memset(N, 0, sizeof(N));

int n, x, c=0;

cin >> n;

for (int ct=0; ct!=n; ++ct)

{

cin >> x;

if (!N[x])

++c;

N[x]=true;

}

cout << c << endl;

for (int ct=1; ct!=1001; ++ct)

{

if (N[ct])

cout << ct << " ";

}

return 0;

}