CF961B 1200

题意

解析

前缀或双指针

代码

//前缀
#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int n,k;
int a[N],b[N],c[N],d[N];
int main(){
    scanf("%d %d",&n,&k);

    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
    }
    for(int i=1;i<=n;i++){
        scanf("%d",&b[i]);
        c[i] = c[i-1] + a[i];
        d[i] = d[i-1] + a[i] * b[i];
    }

    int res = 0;
    for(int i=1;i+k-1<=n;i++){
        int j = i + k - 1;
        res = max(res,d[n] - (d[j] - d[i-1]) + c[j] - c[i-1]);
    }
    printf("%d",res);
    return 0;
}
//双指针
#include<bits/stdc++.h>
using namespace std;
const int N = 1e5+10,M = 1e6+10;
long long sum,ans,a[N],t[N],n,k;
int main(){
	scanf("%d %d",&n,&k);
	for(int i=1;i<=n;i++){
		scanf("%d",&a[i]);
	}
	for(int i=1;i<=n;i++){
		scanf("%d",&t[i]);
	}
	for(int i=1;i<=k;i++){
		sum += a[i];
	}
	for(int i=k+1;i<=n;i++)	
		sum += a[i] * t[i];
	for(int i=1;i + k - 1 <= n;i++){
		ans = max(ans,sum);
		int r = i + k - 1;
		if(t[i] == 0) sum -= a[i];
		if(t[r+1] == 0) sum += a[r+1];
	}
	printf("%d\n",ans);
	return 0;
}