# 【題解】ZeroJudge b130: NOIP2006 1.明明的随机数

#### 【作法-1】array

• 用一個array a[x] 來紀錄每一個 x 出現的次數，1 ≤ x ≤ 1000。
```#include <iostream>
using namespace std;

int main() {
int N, x;
cin >> N;
int a[1001]; //N个1到1000之间的随机整数
for (int i = 0; i <= 1000; i++) {
a[i] = 0; //初始化
}
for (int i = 0; i < N; i++) {
cin >> x;
a[x]++;
}
int ans = 0;
for (int i = 1; i <= 1000; i++) {
if (a[i]) ans++;
}
cout << ans << "\n";
for (int i = 1; i <= 1000; i++) {
if (a[i]) cout << i << " ";
}
cout << "\n";
return 0;
}
```

#### 【作法-2】map

```#include <iostream>
#include <map>
using namespace std;

int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int N, x;
while (cin >> N){
map<int,int> mp;
for (int i=0; i<N; i++){
cin >> x;
if (mp.count(x)) mp[x]++;
else mp[x] = 1;
}
cout << mp.size() << '\n';
for (auto it=mp.begin(); it!=mp.end(); it++){
cout << (*it).first << ' ';
}
cout << '\n';
}
return 0;
}
```

Python code (credit: Amy Chou)

```N = int(input())
lst = list(map(int, input().split()))
lst = list(set(lst))
lst.sort()
print(len(lst))
print(" ".join(list(map(str, lst))))
```