小图灵65pt和洛谷35pt，分数差距有点大，大样例小样例都过了，为什么呢

#include<bits/stdc++.h>
using namespace std;
#define N 100010
#define ll long long
#define F(x,y,z) for(int x=y;x<=z;x++)
#define D(x,y,z) for(int x=y;x>=z;x--)
int n, v[N], a[N], ans, d, minn = 0x3f3f3f3f, p, s[N], m[N], now;
int main() {
//	freopen("road.in","r",stdin);
//	freopen("road.out","w",stdout);
	cin >> n >> d;
	F(i, 1, n - 1) {
		cin >> v[i];
	}
	F(i, 1, n) {
		cin >> a[i];
		if (a[i] < minn) {
			minn = a[i];
			p = i;
		}
		m[i] = p;
	}
	F(i, 1, n - 1) {
		if (m[i] != i) {
			v[m[i]] += v[i];
			v[i] = 0;
		}
	}
	F(i, 1, n - 1) {
		if (now < 0) now = 0;
		int cost = v[i] - now;
		if (cost > 0) {
			ans += (a[m[i]] * (cost / d + ((cost % d == 0) ? 0 : 1)));
			now += (cost / d + ((cost % d == 0) ? 0 : 1)) * d;
		}
		now -= v[i];
		//	cout<<ans<<" "<<now<<endl;
	}
	cout << ans;
}