CF864D Make a Permutation!

思路：

贪心，构造，模拟。

实现：

#include <bits/stdc++.h>
using namespace std;
int t[200005], a[200005], vis[200005], n;
int main()
{
    while (cin >> n)
    {
        memset(t, 0, sizeof t); memset(vis, 0, sizeof vis);
        int cnt = 0;
        for (int i = 0; i < n; i++) 
        {
            cin >> a[i]; t[a[i]]++;
            if (t[a[i]] > 1) cnt++;
        }
        cout << cnt << endl;
        queue<int> q;
        for (int i = 1; i <= n; i++) if (!t[i]) q.push(i);
        for (int i = 0; i < n; i++)
        {
            if (!t[a[i]]) continue;
            else if (t[a[i]] == 1 && !vis[a[i]]) 
            {
                cout << a[i] << " "; t[a[i]]--;
            }
            else 
            {
                if (vis[a[i]]) 
                {    
                    cout << q.front() << " "; q.pop(); 
                }
                else if (q.front() < a[i])
                {
                    cout << q.front() << " "; q.pop(); 
                }
                else 
                {
                    cout << a[i] << " "; vis[a[i]] = 1;
                }
                t[a[i]]--;
            }
        }
        cout << endl;
    }
    return 0;
}