C++ 代码

#include <iostream>
#include <algorithm>
using namespace std;

const int N = 100010;
int a[N];
int l = N;
int r;

int main(){
    // freopen ("a.in","r",stdin);  
    // freopen ("a.out","w",stdout);
    int n;
    cin >> n;
    int id;
    while(cin >> id){
        a[id]++;
        l = min(l, id);
        r = max(r, id);
    }
    int a1,a2;
    for(int i = l; i <= r; i++){
        if (a[i] == 0) a1 = i;
        if (a[i] == 2) a2 = i;
    }
    cout << a1 << " " << a2;
    return 0;
}