feat(codeforces): 799

codeforces/799/b.cc

@@ -0,0 +1,54 @@
+#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;
+
+#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__)
+#else
+#define dbgln(...)
+#define dbg(...)
+#endif
+//  }}}
+
+bitset<10000 + 1> seen;
+void solve() {
+  seen.reset();
+  int n;
+  cin >> n;
+  int a, dups = 0;
+  for (int i = 0; i < n; ++i) {
+    cin >> a;
+    if (seen[a]) {
+      ++dups;
+    } else {
+      seen[a] = true;
+    }
+  }
+
+  int unique = n - dups;
+  cout << (dups & 1 ? unique - 1 : unique) << '\n';
+}
+
+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;
+}
+// }}}