delete pics to save space

history_source/信息学奥赛一本通/1.6.1.7t.cpp

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+#include<cstdio>
+#include<cmath>
+using namespace std;
+int main()
+{
+	double three=sqrt(3),add=0,x;
+	for(int i=1;i>0;i++)
+	{
+		x=(1.0/pow(three,i*2-1))/(double)(i*2-1);
+		if(x<0.000001) break;
+		if(i&1) add+=x;
+		else add-=x;
+	} 
+	printf("%g\n",6*add);
+	return 0;
+}