2017 ACM-ICPC 亚洲区（乌鲁木齐赛区） C. Coconut

//基础题
#include <iostream>
#include <cstring>
using namespace std;
const int N = 1e3 + 5;
int supply[N];
int cost_day[N];

int main()
{
	int t, n, b;
	cin >> t;
	while (t--)
	{
		int sum = 0;
		memset(supply, 0, sizeof(supply));
		memset(cost_day, 0, sizeof(cost_day));
		
		cin >> n >> b;
		for (int i = 0; i < n; i++) cin >> supply[i];
		for (int i = 0; i < n - 1; i++) cin >> cost_day[i];
		
		bool flag = true;
		
		sum += supply[0];
	
		for (int i = 1; i < n; i++)
		{	
			if (sum < b * cost_day[i - 1])
			{
				flag = false;
				break;
			}
			sum -= b * cost_day[i - 1];
			sum += supply[i];
		}
		if (flag) cout << "Yes" << endl;
		else cout << "No" << endl;
		
	}
	return 0;
}