delete pics to save space

history_source/ccf 入门篇/U4/4.3.2.cpp

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+#include<iostream>
+#include<cmath>
+using namespace std;
+int main()
+{
+	long double pi4=0;
+	long long n=1,j=1;
+	do
+	{
+		if(j%2==1) pi4=pi4+1.0/n;
+		else pi4=pi4-1.0/n;
+		n+=2;
+		j++;
+	}while(1.0/n>=0.000001);
+	cout<<pi4*4.0;
+	while(true);
+}