201. 可见的点

https://www.acwing.com/problem/content/submission/code_detail/13342989/

AcWing/201/201.cpp

@@ -0,0 +1,35 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+using std::endl;
+
+const int N = 1005;
+
+int _t, n, phi[N], ans;
+
+int main() {
+    // Init
+    for (int i = 2; i <= 1000; i++) {
+        phi[i] = i;
+    }
+    for (int i = 2; i <= 1000; i++) {
+        if (phi[i] == i) {
+            for (int j = i; j <= 1000; j += i) {
+                phi[j] = phi[j] / i * (i - 1);
+            }
+        }
+    }
+    // End: Init
+
+    cin >> _t;
+    for (int t = 1; t <= _t; t++) {
+        ans = 0;
+        cin >> n;
+        for (int i = 2; i <= n; i++) {
+            ans += phi[i];
+        }
+        cout << t << ' ' << n << ' ' << ans * 2 + 3 << endl;
+    }
+    return 0;
+}