delete pics to save space

2.10140.cpp

@@ -0,0 +1,50 @@
+#include<cstdio>
+#include<cstring>
+#include<cmath>
+#include<algorithm>
+#include<cassert>
+using std::max;
+typedef long long LL;
+const int maxn=1000100;
+bool hsh[maxn];
+LL prime[maxn],cnt;
+LL a[maxn];
+void solve(int L,int R)
+{
+	memset(hsh,true,sizeof(hsh));
+	for(int i=0;i<cnt&&prime[i]*prime[i];i++)
+	{
+		int s=L/prime[i]+(L%prime[i]?1:0);
+		s=(s<2?2:s);
+		for(LL j=s*prime[i];j<=R;j+=prime[i]) hsh[j-L]=false;
+	}
+	int top=0;
+	for(LL i=L;i<=R;i++) if(hsh[i-L]&&i!=1) a[top++]=i;
+	if(top<2) { printf("There are no adjacent primes.\n"); return; }
+	LL Min=2147483647ll,p1=0; LL Max=0,p2=0;
+	for(int i=0;i<top-1;i++)
+	{
+		if(a[i+1]-a[i]<Min) Min=a[i+1]-a[i],p1=i;
+		if(a[i+1]-a[i]>Max) Max=a[i+1]-a[i],p2=i;
+	}
+	printf("%lld,%lld are closest, %lld,%lld are most distant.\n",a[p1],a[p1+1],a[p2],a[p2+1]);
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	memset(hsh,true,sizeof(hsh));
+	for(int i=2;i<maxn;i++)
+	{
+		if(hsh[i]) prime[cnt++]=i;
+		for(int j=0;j<cnt&&prime[j]*i<maxn;j++)
+		{
+			hsh[prime[j]*i]=false;
+			if(i%prime[j]==0) break;
+		}
+	}
+	LL L,R;
+	while(scanf("%lld%lld",&L,&R)==2) solve(L,R);
+	return 0;
+}