21 Days Training // Day 1~4

2. average

A solution that can get 30 :

#include 
using namespace std;

int main() {
    freopen("average.in", "r", stdin);
    freopen("average.out", "w", stdout);
    int N, K;cin >> N >> K;
    long long A[N];
    for (int i=0;i> A[i];
    long long prefix[N+1];
    prefix[0] = 0;
    for (int i=1;i<=N;i++) prefix[i] = prefix[i-1] + A[i-1];
    double avgmax=0;
    for (int i=K;i<=N;i++) {
        for (int j=0;j<=N-i;j++) avgmax = max(avgmax, double(prefix[j+i]-prefix[j])/i);
    }
    printf("%.15lf", avgmax);
    return 0;
}

Complexity : O(n^2)
Constraints :

Expected : 30/30

Not Solution?