STL双端队列写起来很简单的啊，有deque为什么不用呢
```cpp
#include <bits/stdc++.h>
using namespace std;
int m, n, a[10100], ans = 0;
deque <int> b;
int main(){
//freopen(".in","r",stdin);
//freopen(".out","w",stdout);
ios :: sync_with_stdio(false);
cin >> m >> n;
for (int i = 1; i <= n; i++)
cin >> a[i];
for (int i = 1; i <= n; i++){
bool flag = 0;
for (int j = 0; j < b.size(); j++)
if (a[i] == b[j]) {
flag = 1;
break;
}
if (!flag) {
b.push_back(a[i]);
if (b.size() > m) b.pop_front();
ans++;
}
}
cout << ans << endl;
return 0;
}
```
by vivienqkira @ 2017-10-02 19:42:04