feat: 928

codeforces/928/e.cc

@@ -0,0 +1,109 @@
+#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;
+
+using i32 = int32_t;
+using u32 = uint32_t;
+using i64 = int64_t;
+using u64 = uint64_t;
+using f64 = double;
+using f128 = long double;
+
+#if __cplusplus >= 202002L
+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());
+}
+#endif
+
+static void NO() {
+  std::cout << "NO\n";
+}
+
+static void YES() {
+  std::cout << "YES\n";
+}
+
+template <typename T>
+using vec = std::vector<T>;
+
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+#define ff first
+#define ss second
+
+#ifdef LOCAL
+#define db(...) std::print(__VA_ARGS__)
+#define dbln(...) std::println(__VA_ARGS__)
+#else
+#define db(...)
+#define dbln(...)
+#endif
+//  }}}
+
+void solve() {
+  u64 n, k;
+  cin >> n >> k;
+
+  /*
+     initially lays down ceil(n / 2.0) cards
+
+     if found, its just 2 * k
+
+     n - ceil(n / 2.0) left
+
+     lays down 2 * odds
+
+note: only odd # turns matter
+
+     n = 24
+     1 3 5 7 9 11 13 15 17 19 21 23 -> 2 4 6 8 10 12 ... left
+     2 6 10 14
+     div. both sides by 2:
+     1 2 3 4 5 6 <- n - ceil(n / 2.0) left
+     continue, log(n) itme
+     3 9 ... <- don't matter
+
+     div by 2
+     */
+
+  u64 multiplier = 1;
+  while (k > (u64)ceil(n / 2.0)) {
+    k -= (u64)ceil(n / 2.0);
+    n -= (u64)ceil(n / 2.0);
+    multiplier *= 2;
+  }
+
+  println("{}", multiplier * (1 + 2 * (k - 1)));
+}
+
+int main() {  // {{{
+  cin.tie(nullptr)->sync_with_stdio(false);
+  cin.exceptions(cin.failbit);
+
+  u32 tc = 1;
+  cin >> tc;
+
+  for (u32 t = 0; t < tc; ++t) {
+    solve();
+  }
+
+  return 0;
+}
+// }}}