Submission #923044

#	Time	Username	Problem	Language	Result	Execution time	Memory
923044		Ianis	DEL13 (info1cup18_del13)	C++17	15 / 100	8 ms	2528 KiB

del13

#ifdef LOCAL
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cassert>
#include <random>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#else
#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
#define cerr if (false) cerr 
#define endl '\n'
#endif

#define fi first
#define se second

#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()

#define lsb(x) (x & (-x))

#define bit(mask, i) (((mask) >> (i)) & 1)
#define popcount(x) __builtin_popcount(x)

#define YES cout << "YES" << endl
#define NO cout << "NO" << endl

using namespace std;

template <typename T>
bool ckmax(T &a, T b) { return a < b ? a = b, true : false; }
template <typename T>
bool ckmin(T &a, T b) { return a > b ? a = b, true : false; }

using ll = long long;
using pii = pair<int, int>;

const int NMAX = 1e5+5;

struct Node {
   bool removed;
   int l, r;
};

int n, q;
Node a[NMAX];
vector<int> ans;
bool ap[NMAX];

void node_remove(int u) {
   a[u].removed = true;
   int l = a[u].l, r = a[u].r;
   a[l].r = r;
   a[r].l = l;
}

void read() {
   cin >> n >> q;
   fill(ap, ap + n + 1, 0);
   for (int i = 1, x; i <= q; i++) {
      cin >> x;
      ap[x] = 1;
   }
}

void solve() {
   if ((n - q) % 2 == 1) {
      cout << -1 << endl;
      return;
   }

   ap[0] = ap[n + 1] = 1;

   for (int i = 1; i <= n; i++)
      a[i] = { 0, i - 1, i + 1 };

   ans.clear();

   for (int i = 1; i <= n; i++) {
      if (ap[i] || a[i].removed) continue;
      while (!ap[a[i].l] && !ap[a[i].r]) {
         node_remove(a[i].l);
         node_remove(a[i].r);
         ans.push_back(i);
      }
   }

   for (int i = 1; i <= n; i++) {
      if (a[i].removed) continue;
      while (!ap[a[i].l] && !ap[a[i].r]) {
         node_remove(a[i].l);
         node_remove(a[i].r);
         ans.push_back(i);
      }
   }

   if (int(ans.size()) != (n - q) / 2) {
      cout << -1 << endl;
      return;
   }

   cout << ans.size() << endl;
   for (auto &it : ans)
      cout << it << ' ';
   cout << endl;
}

signed main() {
#ifdef LOCAL
   freopen("input.txt", "r", stdin);
#endif
   ios_base::sync_with_stdio(false);
   cin.tie(0);
   cout.tie(0);
   
   int t = 1;
   cin >> t;

   while (t--) {
      read();
      solve();
   }

   return 0;
}

• Subtask 1: 0 / 15
• Subtask 2: 0 / 15
• Subtask 3: 15 / 15
• Subtask 4: 0 / 25
• Subtask 5: 0 / 30