delete pics to save space

history_source/信息学奥赛一本通/1.4.1.20.cpp

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+#include<cstdio>
+using namespace std;
+int main()
+{
+	int n;
+	double a,b,c,ans=0;
+	a=b=c=1;
+	scanf("%d",&n);
+	for(int i=0;i<n;i++)
+	{
+		c=a+b;
+		ans+=c/b;
+		a=b;
+		b=c;
+	}
+	printf("%.4lf\n",ans);
+	return 0;
+}
+