#168. 【模板】线性筛

https://sjzezoj.com/submission/74744

S2OJ/168/168.cpp

@@ -1,76 +1,63 @@
-#pragma GCC optimize("Ofast")
+#include <iostream>
 
-#include <bits/stdc++.h>
+using std::cin;
+using std::cout;
+const char endl = '\n';
 
-using namespace std;
+const int N = 1e6 + 5;
 
-int q, p, op, k, prime[1000005], miu[1000005], phi[1000005];
-long long sig[1000005];
-bool is_prime[1000005];
-
-template <typename T>
-inline void read(T& x) {
-    x = 0;
-    int f = 1;
-    char ch;
-    while (!isdigit(ch = getchar())) {
-        if (ch == '-') f = -1;
-    }
-    while (isdigit(ch)) {
-        x = x * 10 + (ch ^ 48);
-        ch = getchar();
-    }
-    x *= f;
-}
-
-template <typename T>
-void write(T x) {
-    if (x < 0) {
-        putchar('-');
-        x = -x;
-    }
-    if (x > 9) {
-        write(x / 10);
-    }
-    putchar(x % 10 + '0');
-}
+int q, p, primes[N], sig[N], miu[N], phi[N];
+bool is_prime[N];
 
 int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    // ======
+
     phi[1] = miu[1] = sig[1] = 1;
-    for (int i = 2; i <= 1000000; i++) {
+
+    for (int i = 2; i < N; i++) {
         if (!is_prime[i]) {
-            prime[++p] = i;
+            primes[++p] = i;
+
             phi[i] = i - 1;
             miu[i] = -1;
             sig[i] = i + 1;
         }
-        for (int j = 1; j <= p && prime[j] * i <= 1000000; j++) {
-            is_prime[i * prime[j]] = 1, miu[i * prime[j]] = -miu[i];
-            phi[i * prime[j]] = phi[i] * phi[prime[j]];
-            sig[i * prime[j]] = sig[i] * sig[prime[j]];
-            if (i % prime[j] == 0) {
-                miu[i * prime[j]] = 0;
-                phi[i * prime[j]] = phi[i] * prime[j];
-                sig[i * prime[j]] -= sig[i / prime[j]] * prime[j];
+
+        for (int j = 1; j <= p && primes[j] * i < N; j++) {
+            is_prime[i * primes[j]] = 1;
+
+            miu[i * primes[j]] = -miu[i];
+            phi[i * primes[j]] = phi[i] * phi[primes[j]];
+            sig[i * primes[j]] = sig[i] * sig[primes[j]];
+
+            if (i % primes[j] == 0) {
+                miu[i * primes[j]] = 0;
+                phi[i * primes[j]] = phi[i] * primes[j];
+                sig[i * primes[j]] -= sig[i / primes[j]] * primes[j];
+
                 break;
             }
         }
     }
-    read(q);
-    for (int i = 0; i < q; i++) {
-        read(op);
-        read(k);
+
+    // ======
+
+    cin >> q;
+
+    while (q--) {
+        int op, k;
+
+        cin >> op >> k;
+
         if (op == 1) {
-            write(prime[k]);
-            putchar('\n');
-        } else {
-            write(sig[k]);
-            putchar(' ');
-            write(miu[k]);
-            putchar(' ');
-            write(phi[k]);
-            putchar('\n');
+            cout << primes[k] << endl;
+        } else {  // op == 2
+            cout << sig[k] << ' ' << miu[k] << ' ' << phi[k] << endl;
         }
     }
+
     return 0;
 }