t2 80分求调

#include<bits/stdc++.h>
using namespace std;
long long n,d,v[100005],a[100005];
long long ans=0,shengyu=0;
int main(){
//	freopen("road.in","r",stdin);
//	freopen("road.out","w",stdout);
	cin>>n>>d;
	if(n==1){
		cout<<0;
		return 0;
	}
	for(int i=1;i<n;i++){
		cin>>v[i];
	}
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	for(int i=1;i<n;){
		int j=i;
		long long need=0;
		while(a[j]>=a[i]&&j<=n){
			need+=v[j];
			j++;
		}
		if(need>shengyu){
			if((need-shengyu)%d==0){
				ans+=(need-shengyu)/d*a[i];
			}
			else{
				ans+=((need-shengyu)/d+1)*a[i];	
			}
			if((need-shengyu)%d!=0){
				shengyu=((need-shengyu)/d+1)*d-(need-shengyu); 
			}
		}
		i=j;
	}
	cout<<ans;
	return 0;
} 
/*
5 4
10 10 10 10
9 8 9 6 5
*/

玄关