#1023. [NOIP2015四校联训Day8]质数生成器

https://sjzezoj.com/submission/36746

S2OJ/1023/1023.cpp

@@ -0,0 +1,82 @@
+#pragma GCC optimize("Ofast")
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int t, n, m, phi[1000005], cnt, prime[1000005];
+bool vis[1000005];
+
+void euler(int n) {
+    phi[1] = 1;
+    for (int i = 2; i <= n; i++) {
+        if (!vis[i]) {
+            phi[i] = i - 1;
+            prime[++cnt] = i;
+        }
+        for (int j = 1; j <= cnt; j++) {
+            if (1ll * i * prime[j] >= n) break;
+            vis[i * prime[j]] = true;
+            if (i % prime[j]) {
+                phi[i * prime[j]] = phi[i] * (prime[j] - 1);
+            } else {
+                phi[i * prime[j]] = phi[i] * prime[j];
+                break;
+            }
+        }
+    }
+}
+
+int find(int l, int r, int x) {
+    int res = 0;
+    while (l <= r) {
+        int mid = (l + r) >> 1;
+        if (prime[mid] >= x) {
+            res = mid;
+            r = mid - 1;
+        } else {
+            l = mid + 1;
+        }
+    }
+    return res;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin >> t;
+    euler(1000000);
+    while (t--) {
+        memset(vis, 0x00, sizeof(vis));
+        cin >> m >> n;
+        if (n <= 1000000) {
+            int l = find(0, cnt, m);
+            for (int i = l; i <= cnt; i++) {
+                if (prime[i] > n) break;
+                cout << prime[i] << endl;
+            }
+        } else {
+            int l = m + (m & 1);
+            if (l == 2) l += 2;
+            for (int i = l; i <= n; i += 2) {
+                vis[i - m] = true;
+            }
+            int d = sqrt(n) + 1;
+            for (int i = 2; i <= cnt; i++) {
+                if (prime[i] > d) break;
+                int p = (m - 1) / prime[i] + 1;
+                p += !(p & 1);
+                if (p == 1) p += 2;
+                for (int j = p; j * prime[i] <= n; j++) {
+                    vis[j * prime[i] - m] = true;
+                }
+            }
+            for (int i = m; i <= n; i++) {
+                if (!vis[i - m]) {
+                    cout << i << '\n';
+                }
+            }
+        }
+        cout << endl;
+    }
+    return 0;
+}