feat(cses): a few problems

cses/two-sets/solution.cc

@@ -0,0 +1,89 @@
+#include <bits/stdc++.h>  // {{{
+
+// https://codeforces.com/blog/entry/96344
+
+#pragma GCC optimize("O2,unroll-loops")
+#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
+
+using namespace std;
+
+template <typename T>
+constexpr T MIN = std::numeric_limits<T>::min();
+
+template <typename T>
+constexpr T MAX = std::numeric_limits<T>::max();
+
+template <typename T>
+[[nodiscard]] static T sc(auto &&x) {
+  return static_cast<T>(x);
+}
+
+template <typename T>
+[[nodiscard]] static T sz(auto &&x) {
+  return static_cast<T>(x.size());
+}
+
+using ll = long long;
+using ld = long double;
+template <typename T>
+using vec = std::vector<T>;
+template <typename T, size_t N>
+using arr = std::array<T, N>;
+
+#define ff first
+#define ss second
+#define eb emplace_back
+#define pb push_back
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+//  }}}
+
+struct hash_pair {
+  size_t operator()(const pair<int, int> &p) const {
+    return hash<int>()(p.first) ^ (hash<int>()(p.second) << 1);
+  }
+};
+
+void solve() {
+  ll n;
+  cin >> n;
+
+  ll full = n * (n + 1) / 2;
+  if (full & 1) {
+    cout << "NO\n";
+    return;
+  }
+  ll half = full / 2;
+
+  vec<int> ans1, ans2;
+  ll total1 = 0;
+
+  for (int i = n; i >= 1; --i) {
+    if (total1 + i <= half) {
+      ans1.eb(i);
+      total1 += i;
+    } else {
+      ans2.eb(i);
+    }
+  }
+
+  cout << ans1.size() << endl;
+  for (auto e : ans1)
+    cout << e << ' ';
+  cout << endl;
+  cout << ans2.size() << endl;
+  for (auto e : ans2)
+    cout << e << ' ';
+  cout << endl;
+
+  cout << endl;
+}
+
+int main() {  // {{{
+  cin.tie(nullptr)->sync_with_stdio(false);
+
+  solve();
+
+  return 0;
+}
+// }}}