CF1023D Array Restoration

思路：

使用set即可，细节很多，容易出错。

实现：

#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const int MAXN = 200005;
int a[MAXN], l[MAXN], r[MAXN];
int main()
{
    int n, q;
    while (cin >> n >> q)
    {
        for (int i = 1; i <= q; i++) { l[i] = INF; r[i] = -INF; }
        int c0 = 0, cq = 0;
        for (int i = 1; i <= n; i++) 
        {
            cin >> a[i];
            c0 += a[i] == 0;
            cq += a[i] == q;
            if (a[i] == 0) continue;
            l[a[i]] = min(l[a[i]], i);
            r[a[i]] = max(r[a[i]], i);
        }
        if (!c0 && !cq) { cout << "NO" << endl; continue; }
        set<int> st;
        bool flg = true;
        for (int i = 1; i <= n; i++)
        {
            if (i == l[a[i]]) st.insert(a[i]);
            if (a[i] && !st.empty() && *st.rbegin() != a[i]) { flg = false; break; }
            int tmp = -1;
            if (a[i] == 0)
            {
                if (cq == 0) { tmp = q; cq++; }
                else if (!st.empty()) tmp = *st.rbegin();
                else tmp = 1;
            }
            if (i == r[a[i]]) st.erase(st.find(a[i]));
            if (tmp != -1) a[i] = tmp;
        }
        if (!cq || !flg) { cout << "NO" << endl; continue; }
        cout << "YES" << endl;
        for (int i = 1; i <= n; i++) cout << a[i] << " ";
        cout << endl;
    }
    return 0;
}