[SDCPC2023] Orders

**【题目描述】** 某工厂在第 $1$ 天开工之前收到了 $n$ 笔订单，第 $i$ 笔订单可以用两个整数 $a_i$ 和 $b_i$ 描述，表示工厂需要在第 $a_i$ 天结束时交付 $b_i$ 件货物。 已知工厂每天能生产 $k$ 件货物，且第 $1$ 天开工之前没有任何存货，问该工厂能否完成所有订单。 **【输入格式】** 有多组测试数据。第一行输入一个整数 $T$（$1 \le T \le 100$）表示测试数据组数，对于每组测试数据： 第一行输入两个整数 $n$ 和 $k$（$1 \le n \le 100$，$1 \le k \le 10^9$）表示订单数量以及工厂每日能生产的货物数量。 对于接下来 $n$ 行，第 $i$ 行输入两个整数 $a_i$ 和 $b_i$（$1 \le a_i, b_i \le 10^9$）表示第 $i$ 笔订单要求在第 $a_i$ 天结束时交付 $b_i$ 件货物。 **【输出格式】** 每组数据输出一行。若工厂能完成所有订单输出 $\texttt{Yes}$，否则输出 $\texttt{No}$。 **【样例解释】** 对于第一组样例数据，工厂每天能生产 $5$ 件货物。 - 在第 $1$ 天结束时，工厂共有 $5$ 件货物，可以完成第 $2$ 笔订单。交付后，工厂剩余 $2$ 件货物。 - 在第 $6$ 天结束时，工厂又多生产了 $25$ 件货物，共有 $27$ 件货物，可以完成第 $1$ 和第 $3$ 笔订单。交付后，工厂剩余 $0$ 件货物。 - 在第 $8$ 天结束时，工厂又多生产了 $10$ 件货物，共有 $10$ 件货物，可以完成第 $4$ 笔订单。交付后，工厂剩余 $9$ 件货物。 对于第二组样例数据，工厂每天能生产 $100$ 件货物。 - 在第 $3$ 天结束时，工厂共有 $300$ 件货物，可以完成第 $1$ 笔订单。交付后，工厂剩余 $100$ 件货物。 - 在第 $4$ 天结束时，工厂又多生产了 $100$ 件货物，共有 $200$ 件货物，无法完成第 $2$ 笔订单。

A factory receives $n$ orders at the beginning of day $1$. The $i$-th order can be described as two integers $a_i$ and $b_i$, indicating that at the end of day $a_i$, the factory needs to deliver $b_i$ products to the customer. Given that the factory can produce $k$ products each day, and at the beginning of day $1$ the factory has no product in stock, can the factory complete all orders?

There are multiple test cases. The first line of the input contains an integer $T$ ($1 \le T \le 100$) indicating the number of test cases. For each test case: The first line contains two integers $n$ and $k$ ($1 \le n \le 100$, $1 \le k \le 10^9$) indicating the number of orders and the number of products the factory can produce each day. For the following $n$ lines, the $i$-th line contains two integers $a_i$ and $b_i$ ($1 \le a_i, b_i \le 10^9$) indicating that the $i$-th order require the factory to deliver $b_i$ products at the end of day $a_i$.

For each test case output one line. If the factory can complete all orders output $\texttt{Yes}$, otherwise output $\texttt{No}$.

2
4 5
6 12
1 3
6 15
8 1
3 100
3 200
4 300
6 100

Yes
No

For the first sample test case, the factory can produce $5$ products each day. - At the end of day $1$, there are $5$ products in stock so the factory can complete the $2$-nd order. After delivery, there are $2$ products left in stock. - At the end of day $6$, the factory produces $25$ more products. There are $27$ products in stock so the factory can complete the $1$-st and the $3$-rd order. After delivery, there are $0$ products left in stock. - At the end of day $8$, the factory produces $10$ more products. There are $10$ products in stock so the factory can complete the $4$-th order. After delivery, there are $9$ products left in stock. For the second sample test case, the factory can produce $100$ products each day. - At the end of day $3$, there are $300$ products in stock and the factory can complete the $1$-st order. After delivery, there are $100$ products left in stock. - At the end of day $4$, the factory produces $100$ more products. There are only $200$ products in stock so the factory cannot complete the $2$-nd order.