poj 2018 Best Cow Fences

求一段长为n序列的最大平均值子序列，子序列的长度最小为F.

类似于最大连续字段和的做法

#include <iostream>#define MAXN 100010using namespace std ;__int64 a[MAXN] , sum[MAXN] ;int main (){__int64 n , m , i , j , k , s , ncows , nfields ;scanf ("%I64d%I64d" , &n , &m) ;for (i = 0 ; i < n ; i ++)scanf ("%I64d" , &a[i]) ;for (sum[m - 1] = i = 0 ; i < m ; i ++)sum[m - 1] += a[i] ;for (; i < n ; i ++)sum[i] = sum[i - 1] - a[i - m] + a[i] ;for (i = m , s = ncows = sum[i - 1] , j = nfields = i ; i < n ; i ++){if ((s + a[i]) * m < sum[i] * (j + 1))s = sum[i] , j = m ;elses += a[i] , j ++ ;if (s * nfields > ncows * j)ncows = s , nfields = j ;}printf ("%I64d/n" , 1000*ncows/nfields) ;return 0 ;}