筛法求素数

A.cpp

@@ -0,0 +1,22 @@
+#include<bits/stdc++.h>
+
+using namespace std;
+const int N = 101;
+vector<bool> prime(N, true);
+
+void fill() {
+    prime[0] = prime[1] = false;
+    for (int i = 2; i * i <= N; i++)
+        if (prime[i])
+            for (int j = i * i; j < N; j += i)
+                prime[j] = false;
+}
+
+int main() {
+    fill();
+    int n;
+    cin >> n;
+    for (int i = 2; i <= n; i++)
+        if (prime[i])cout << i << endl;
+    return 0;
+}