delete pics to save space

history_source/挑战程序设计竞赛/2.6.2.3.cpp

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+#include<cstdio>
+#include<cmath>
+#include<cstring>
+#include<algorithm>
+using namespace std;
+#define ll long long
+ll a,b;
+bool is_prime[1000001],is_prime_small[1000001];
+void solve()
+{
+	ll i,j,ans=0;
+	memset(is_prime_small,1,sqrt(b));
+	memset(is_prime,1,b-a);
+	for(i=2;i*i<b;i++)
+		if(is_prime_small[i])
+		{
+			for(j=2*i;j*j<b;j+=i) is_prime_small[j]=0;
+			for(j=max(2LL,(a+i-1)/i)*i;j<b;j+=i) is_prime[j-a]=0;
+		}
+	for(i=a;i<b;i++) ans+=is_prime[i-a];
+	printf("%lld\n",ans);
+}
+int main()
+{
+	scanf("%lld%lld",&a,&b);
+	solve();
+	return 0;
+}
+//22 37
+//22801763489 22801787297