C. Coconut（2017 ACM-ICPC 亚洲区（乌鲁木齐赛区）网络赛）

额，只是一道签到题,emmm直接代码：

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 using namespace std;

 const int maxn = ;
 int c[maxn];
 int d[maxn];

 int main(){
     int t;
     scanf("%d", &t);
     while (t--){
         int n, m;
         scanf("%d %d", &n, &m);
         for (int i = ; i < n; i++){
             scanf("%d", &c[i]);
         }
         for (int i = ; i < n - ; i++){
             scanf("%d", &d[i]);
         }
         d[n-] = ;
         int ans = ;
         int i;
         for (i = ; i < n; i++){
             ans = ans + c[i] - m*d[i];
             if (ans < )
                 break;
         }
         if (i == n)
             printf("Yes\n");
         else
             printf("No\n");
     }
     //system("pause");
     return ;
 }