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November 8, 2025 10:33
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| #include <bits/stdc++.h> | |
| using namespace std; | |
| #define ll long long | |
| #define endl '\n' | |
| void solve() { | |
| ll n; | |
| if (!(cin >> n)) return; | |
| vector<ll> a(n); | |
| for (ll i = 0; i < n; i++) cin >> a[i]; | |
| // k is half the current array (n is even) | |
| ll k = n / 2; | |
| // Quick 1-op check on the WHOLE array as one subsequence of length n | |
| // Conditions with k=n/2: | |
| // 1) max(first k) < min(last k) OR | |
| // 2) min(first k) > max(last k) | |
| ll mxL = a[0], mnR = a[k]; | |
| for (ll i = 1; i < k; i++) mxL = max(mxL, a[i]); | |
| for (ll i = k + 1; i < n; i++) mnR = min(mnR, a[i]); | |
| bool ok1 = (mxL < mnR); | |
| ll mnL = a[0], mxR = a[k]; | |
| for (ll i = 1; i < k; i++) mnL = min(mnL, a[i]); | |
| for (ll i = k + 1; i < n; i++) mxR = max(mxR, a[i]); | |
| bool ok2 = (mnL > mxR); | |
| if (ok1 || ok2) { | |
| // 1 operation: whole array is deletable | |
| cout << 1 << endl; | |
| cout << n << endl; | |
| for (ll i = 0; i < n; i++) cout << a[i] << (i + 1 == n ? '\n' : ' '); | |
| return; | |
| } | |
| // 2 operations guaranteed for a permutation of 1..n | |
| // Let L = {1..k} and R = {k+1..n} | |
| // First subsequence: pick L from left and R from right (preserving order) | |
| vector<ll> leftIdx, rightIdx; | |
| ll i = 0, j = n - 1; | |
| while (i < j) { | |
| while (i < j && !(1 <= a[i] && a[i] <= k)) i++; | |
| while (i < j && !(k + 1 <= a[j] && a[j] <= n)) j--; | |
| if (i < j) { | |
| leftIdx.push_back(i); | |
| rightIdx.push_back(j); | |
| i++; j--; | |
| } | |
| } | |
| // Build the first subsequence values in array order | |
| vector<ll> firstSub; | |
| for (ll p : leftIdx) firstSub.push_back(a[p]); | |
| reverse(rightIdx.begin(), rightIdx.end()); | |
| for (ll p : rightIdx) firstSub.push_back(a[p]); | |
| // Collect remaining (second subsequence) values | |
| vector<char> used(n, 0); | |
| for (ll p : leftIdx) used[p] = 1; | |
| for (ll p : rightIdx) used[p] = 1; | |
| vector<ll> secondSub; | |
| for (ll t = 0; t < n; t++) if (!used[t]) secondSub.push_back(a[t]); | |
| // Output | |
| cout << 2 << endl; | |
| cout << (ll)firstSub.size() << endl; | |
| for (ll t = 0; t < (ll)firstSub.size(); t++) | |
| cout << firstSub[t] << (t + 1 == (ll)firstSub.size() ? '\n' : ' '); | |
| cout << (ll)secondSub.size() << endl; | |
| for (ll t = 0; t < (ll)secondSub.size(); t++) | |
| cout << secondSub[t] << (t + 1 == (ll)secondSub.size() ? '\n' : ' '); | |
| } | |
| int main() { | |
| ios::sync_with_stdio(false); | |
| cin.tie(nullptr); | |
| solve(); | |
| return 0; | |
| } |
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