feat(codeforces/944): a-g

codeforces/944/f.cc

@@ -0,0 +1,71 @@
+#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;
+//  }}}
+
+void solve() {
+  u32 r;
+  cin >> r;
+  u64 ans = 0;
+
+  for (u64 y = 1; y <= r; ++y) {
+    i64 hi_x, lo_x;
+
+    {
+      i64 l = 0, h = r;
+      while (l <= h) {
+        i64 m = l + (h - l) / 2;
+        if (m * m + y * y < (u64)r * r) {
+          l = m + 1;
+        } else {
+          h = m - 1;
+        }
+      }
+      lo_x = l;
+    }
+
+    {
+      i64 l = 0, h = r;
+      while (l <= h) {
+        i64 m = l + (h - l) / 2;
+        if (m * m + y * y < ((u64)r + 1) * (r + 1)) {
+          l = m + 1;
+        } else {
+          h = m - 1;
+        }
+      }
+      hi_x = h;
+    }
+
+    ans += (hi_x - lo_x + 1) * 4;
+  }
+
+  cout << ans << '\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;
+}
+// }}}