论官方数据有多水

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,d,v[114514],a[114514],dp[114514],vv,va,lai=1,bet;
void solve(){
    vv=v[n-1];
    dp[1]=(a[1]*((vv+d-1)/d));
    for(int i=2;i<=n;i++){
        va=v[i-1]-v[i-2];
        bet=((va-bet+d-1)/d*d)%(va-bet);
        //cout<<i<<':'<<dp[i-1]<<' '<<bet<<' '<<a[lai]*((vv-bet-v[i-1]+d-1)/d)<<' '<<a[i]*((vv-bet-v[i-1]+d-1)/d)<<endl;
        if(dp[i-1]>dp[i-1]-(a[lai]*((vv-bet-v[i-1]+d-1)/d))+(a[i]*((vv-bet-v[i-1]+d-1)/d))){
            dp[i]=dp[i-1]-(a[lai]*((vv-bet-v[i-1]+d-1)/d))+(a[i]*((vv-bet-v[i-1]+d-1)/d));
            lai=i;
        }
        else{
            dp[i]=dp[i-1];
        }
    }
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    //freopen("road.in","r",stdin);
    //freopen("road.out","w",stdout);
    cin>>n>>d;
    for(int i=1;i<=n-1;i++){
        cin>>vv;
        v[i]=v[i-1]+vv;
    }
    for(int i=1;i<=n;i++){
        cin>>a[i];
        dp[i]=1145141919810ll;
    }
    solve();
    cout<<dp[n]<<endl;
    return 0;
}