JAVA课程08

        final int max=1000;
        double item=0;
        double sum=0;
        int flag=-1;
         
        int n=0;
        for(n=0;n<=max;n++)
        {
            flag*=-1;
            item=flag*1.0/(2*n+1);
            sum += item;
        }
        System.out.println(4*sum);