feat(codeforces/970): a-f

codeforces/970/b.cc

@@ -0,0 +1,130 @@
+#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 d64 = double;
+using d128 = long double;
+template <typename T>
+using vec = std::vector<T>;
+template <typename T, size_t N>
+using arr = std::array<T, N>;
+template <typename T1, typename T2>
+using pai = std::pair<T1, T2>;
+
+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());
+}
+
+static void NO() {
+  std::cout << "No\n";
+}
+
+static void YES() {
+  std::cout << "Yes\n";
+}
+
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+
+#ifdef LOCAL
+#define db(...) std::print(__VA_ARGS__)
+#define dbln(...) std::println(__VA_ARGS__)
+#else
+#define db(...)
+#define dbln(...)
+#endif
+//  }}}
+
+void solve() {
+  u32 n;
+  string s;
+  cin >> n >> s;
+
+  i64 cols = -1;
+  for (u32 i = 0; i < n; ++i) {
+    if (s[i] == '0') {
+      cols = i - 1;
+      break;
+    }
+  }
+
+  if (cols == -1) {
+    if (n == 4)
+      YES();
+    else
+      NO();
+    return;
+  }
+
+  // NOTE: didn't check it was square, holy shit throw
+  if (cols == 0 || n % cols != 0 || cols * cols != n) {
+    NO();
+    return;
+  }
+
+  vec<vec<char>> board(n / cols, vec<char>(cols));
+  for (u32 i = 0; i < board.size(); ++i) {
+    for (u32 j = 0; j < board[i].size(); ++j) {
+      board[i][j] = s[i * cols + j];
+    }
+  }
+
+  u32 zeroes = 0;
+  for (auto c : s)
+    if (c == '0')
+      ++zeroes;
+  for (u32 i = 0; i < cols; ++i) {
+    if (s[i] == '0' || s[n - cols + i] == '0') {
+      NO();
+      return;
+    }
+  }
+  for (u32 i = 0; i < n; i += cols) {
+    if (s[i] == '0' || s[i + cols - 1] == '0') {
+      NO();
+      return;
+    }
+  }
+
+  if (n - 2 * cols - 2 * (n / cols) + 4 != zeroes) {
+    NO();
+  } else {
+    YES();
+  }
+}
+
+int main() {  // {{{
+  cin.tie(nullptr)->sync_with_stdio(false);
+  cin.exceptions(cin.failbit);
+
+  int tc = 1;
+  cin >> tc;
+
+  for (int t = 0; t < tc; ++t) {
+    solve();
+  }
+
+  return 0;
+}
+// }}}