#168. 【模板】线性筛

https://sjzezoj.com/submission/25484

S2OJ/168/168.cpp

@@ -0,0 +1,76 @@
+#pragma GCC optimize("Ofast")
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+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 main() {
+    phi[1] = miu[1] = sig[1] = 1;
+    for (int i = 2; i <= 1000000; i++) {
+        if (!is_prime[i]) {
+            prime[++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];
+                break;
+            }
+        }
+    }
+    read(q);
+    for (int i = 0; i < q; i++) {
+        read(op);
+        read(k);
+        if (op == 1) {
+            write(prime[k]);
+            putchar('\n');
+        } else {
+            write(sig[k]);
+            putchar(' ');
+            write(miu[k]);
+            putchar(' ');
+            write(phi[k]);
+            putchar('\n');
+        }
+    }
+    return 0;
+}