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cses/sorting-and-searching/towers.cc

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+#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>
+[[nodiscard]] static T MIN() {
+  return std::numeric_limits<T>::min();
+}
+
+template <typename T>
+[[nodiscard]] static T MAX() {
+  return 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());
+}
+
+#define prln(...) std::println(__VA_ARGS__)
+#define pr(...) std::print(__VA_ARGS__)
+
+#ifdef LOCAL
+#define dbgln(...) std::println(__VA_ARGS__)
+#define dbg(...) std::print(__VA_ARGS__)
+#endif
+
+using ll = long long;
+using ld = long double;
+template <typename T>
+using ve = std::vector<T>;
+template <typename T, size_t N>
+using ar = std::array<T, N>;
+template <typename T1, typename T2>
+using pa = std::pair<T1, T2>;
+template <typename... Ts>
+using tu = std::tuple<Ts...>;
+template <typename... Ts>
+using dq = std::deque<Ts...>;
+template <typename... Ts>
+using qu = std::queue<Ts...>;
+template <typename... Ts>
+using pq = std::priority_queue<Ts...>;
+template <typename... Ts>
+using st = std::stack<Ts...>;
+
+#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()
+//  }}}
+
+void solve() {
+  int n;
+  cin >> n;
+  ve<int> cubes(n);
+  for (auto& e : cubes)
+    cin >> e;
+
+  multiset<int> towers;
+  /*
+     tower only on smaller, minimize total
+     <- stack highest possible
+
+     a[i] >= a[i + 1] >= ...
+
+     x > y
+     x
+     y
+
+     stack blocks on the smallest accomodating block
+
+     aka, for each cube, upper_bound it, and stack; if nothing, then add new
+     tower
+
+     3,2,1 8,5
+NOTE: forgot that must be strictly greater
+
+10 4 5 9 4 10 2 7 4 6
+
+NOTE: didn't use multiset, + erasewd at *it instead of it
+NOTE: didn't think explicitly about above example
+
+if 10 and need to add 4, doing 10 4 vs 10,4 is the same
+because  alarger number can either next be:
+
+10,4 9 or 10,9 4 (NO DIFFFERENCE)
+     */
+
+  for (auto cube : cubes) {
+    auto it = towers.upper_bound(cube);
+    if (it != towers.end()) {
+      towers.erase(it);
+    }
+    towers.insert(cube);
+  }
+
+  cout << towers.size() << endl;
+}
+
+int main() {  // {{{
+  cin.tie(nullptr)->sync_with_stdio(false);
+  cin.exceptions(cin.failbit);
+
+  int t = 1;
+  // cin >> t;
+  while (t--) {
+    solve();
+  }
+
+  return 0;
+}
+// }}}