二次联通门 : 

 

 

 

 

/*    BZOJ 1011: [HNOI2008]遥远的行星    给跪了。。    模糊预估算法    由精度误差的保证来计算答案*/#include 
     
      #include 
      
       #define Max 100005#define rg registertypedef double flo; flo m[Max], s[Max];int main (int argc, char *argv[]) {    int N; flo A, Answer = 0; scanf ("%d%lf", &N, &A); rg int i, j, k;    for (i = 1; i <= N; ++ i)    {        j = (int) (A * i + 1e-8);        scanf ("%lf", &m[i]); Answer = 0;        if (i <= 500) for (k = 1; k <= j; ++ k) Answer += m[k] * m[i] / (i - k);        else Answer = s[j] * m[i] / (i - j / 2);        printf ("%f\n", Answer); s[i] = s[i - 1] + m[i];    }    return 0;}