P9556 [SDCPC 2023] Orders

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 $\texttt{No}$.

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.