【codeforces 808】B.Average Sleep Time
2017-05-16 22:20
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题目链接:http://codeforces.com/contest/808/problem/B
题意:就是n个数,求连续的k个数相加之和的平均值。
题意:就是n个数,求连续的k个数相加之和的平均值。
#include <iostream> #include <cstdio> using namespace std; int a[200002]; double f[200002]; //用f[i]存放到第i个位置是,前面数的和,预处理下即可 int main() { int n,k; scanf("%d %d",&n,&k); for(int i=0;i<n;i++){ scanf("%d",&a[i]); } f[0]=a[0]; for(int i=1;i<n;i++){ f[i]=f[i-1]+a[i]; } double sum=f[k-1]; for(int i=1,j=i+k-1;i+k-1<n&&j<n;i++,j++){ sum+=f[j]-f[i-1]; } printf("%lf\n",sum/(n-k+1)); return 0; }
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