add aloha/2025hcpc

storage/aloha/cpp/2025hcpc-div1-D.cpp

@@ -0,0 +1,52 @@
+#include <iostream>
+
+using namespace std;
+using ll = long long;
+
+ll N;
+ll ans;
+
+void init();
+void solve();
+
+int main() {
+    ios_base::sync_with_stdio(0);
+    cin.tie(0); cout.tie(0);
+
+    init();
+    solve();
+    cout << ans << "\n";
+}
+
+void init() {
+    cin >> N;
+}
+void solve() {
+    ll temp = 0;
+
+    if (N % 6 == 0) {
+        temp += N*(N-1)*(N-2) / 6;
+        temp -= N/3;
+        temp -= ((N-4)/2) * N;
+        temp /= N;
+        temp += (N-2)/2;
+    } else if (N % 3 == 0) {
+        temp += N*(N-1)*(N-2) / 6;
+        temp -= N/3;
+        temp -= ((N-3)/2) * N;
+        temp /= N;
+        temp += (N-1)/2;
+    } else if (N % 2 == 0){
+        temp += N*(N-1)*(N-2) / 6;
+        temp -= ((N-2)/2)*N;
+        temp /= N;
+        temp += (N-2)/2;
+    } else {
+        temp += N*(N-1)*(N-2) / 6;
+        temp -= ((N-1)/2) * N;
+        temp /= N;
+        temp += (N-1)/2;
+    }
+
+    ans = temp;
+}