momo严选

#include <bits/stdc++.h>
using namespace std;
int main()
{
    freopen("road.in","r",stdin);
    freopen("road.out","w",stdout);
    int n,d;
    cin>>n>>d;
    int v[n+10],a[n+10];
    for (int i=1;i<=n-1;i++)
        {
            cin>>v[i];
        }
    for (int i=1;i<=n;i++)
        {
            cin>>a[i];
        }
    long long ans=0,oil=100000000,dis=0;
    long double tmp=0;
    for(int i=1;i<=n-1;i++)
        {
            if (a[i]<oil)
            {
                dis-=d*tmp;
                long long t=ceil(1.0*dis/d);
                tmp=t-1.0*dis/d;
                ans+=t*oil;
                dis=0;
                oil=a[i];
            }
            dis+=v[i];
        }
    dis-=d*tmp;
    long long res=ans+ceil(1.0*dis/d)*oil;
    cout<<res;
    fclose(stdin);
    fclose(stdout);
    return 0;
}