OJ-Problems-Source/HDOJ/2011_autoAC.cpp

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#include<stdio.h>
int n;
double rev(int c)
{
return c <= n ?( ((c & 1) ? 1.0 : -1.0) / c + rev(c + 1) ): 0 ;
}
int main()
{
int t;
scanf("%d", &t);
while (t-- && scanf("%d", &n))
printf("%.2lf\n", rev(1));
return 0;
}