https://cdn.luogu.com.cn/upload/image_hosting/swondxzx.png

我的code

#include<bits/stdc++.h>
using namespace std;
int n,a[200005],s[200005],m;
int main(){
	scanf("%d",&n);
	scanf("%d",&m);
	for(int i=1;i<=n;i++){
		scanf("%d",&a[i]);
		s[i]=s[i-1]+a[i];
	}
	for(int i=1,l,k;i<=m;i++){
		scanf("%d %d",&l,&k);
		int L=l,R=n+1;
		k=a[l]+k;
		while(L+1<R){
			int mid=(L+R)/2;
			if(a[mid]<k){
				L=mid;
			}else{
				R=mid;
			}
		}
		double f=(double)(s[L]-s[l-1])/(L-l+1);
		printf("%.9lf\n",f);
	}
	return 0;
}

爆零全wa