delete pics to save space

2023-08-03 09:22:52 +08:00
commit de60cd6ed4
1334 changed files with 66221 additions and 0 deletions
--- a/1.2158.cpp
+++ b/1.2158.cpp
@ -0,0 +1,37 @@
+#include<cstdio>
+#include<cstring>
+#include<cmath>
+#include<algorithm>
+using namespace std;
+const int maxn=40005;
+int n,res;
+bool isp[maxn];
+int p[maxn],cnt,phi[maxn];
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	scanf("%d",&n);
+	if(n==1) { puts("0"); return 0; }
+	phi[1]=1;
+	memset(isp,true,sizeof(isp));
+	isp[1]=false;
+	for(int i=2;i<=n-1;i++)
+	{
+		if(isp[i]) { p[cnt++]=i; phi[i]=i-1; }
+		for(int j=0;j<cnt&&i*p[j]<=n-1;j++)
+		{
+			isp[i*p[j]]=false;
+			if(i%p[j]==0)
+			{
+				phi[i*p[j]]=phi[i]*p[j];
+				break;
+			}
+			else phi[i*p[j]]=phi[i]*(p[j]-1);
+		}
+	}
+	for(int i=1;i<=n-1;i++) res+=phi[i];
+	printf("%d\n",res*2+1);
+	return 0;
+}