C++ hdoj 2011 多项式求和

#include<iostream>#include<iomanip>using namespace std;int main(){  int m,n;  double sum;  cin>>m;  while(m--)   { sum=0.0;    //这步容易忘     int j;     cin>>n;     for(j=1;j<=n;j++)     {       if(j%2==0)       sum-=1.0/j;       else       sum+=1.0/j;     }    cout<<setprecision(2)<<std::fixed<<sum<<endl;   } return 0;}