Ferry Loading

Before bridges were common, ferries were used to transport cars across rivers. River ferries, unlike their larger cousins, run on a guide line and are powered by the river's current. Cars drive onto the ferry from one end, the ferry crosses the river, and the cars exit from the other end of the ferry.

There is an l-meter-long ferry that crosses the river. A car may arrive at either river bank to be transported by the ferry to the opposite bank. The ferry travels continuously back and forth between the banks so long as it is carrying a car or there is at least one car waiting at either bank. Whenever the ferry arrives at one of the banks, it unloads its cargo and loads up cars that are waiting to cross as long as they fit on its deck. The cars are loaded in the order of their arrival and the ferry's deck accommodates only one lane of cars. The ferry is initially on the left bank where it had mechanical problems and it took quite some time to fix it. In the meantime, lines of cars formed on both banks that wait to cross the river.

The first line of input contains c, the number of test cases. Each test case begins with the number l, a space and then the number m. m lines follow describing the cars that arrive in this order to be transported. Each line gives the length of a car (in centimeters), and the bank at which the car awaits the ferry ("left" or "right").

For each test case, output one line giving the number of times the ferry has to cross the river in order to serve all waiting cars.

Sample input

4

20 4

380 left

720 left

1340 right

1040 left

15 4

380 left

720 left

1340 right

1040 left

15 4

380 left

720 left

1340 left

1040 left

15 4

380 right

720 right

1340 right

1040 right

Output for sample input

3

3

5

6

This problem can be easily solved using your queue data structure (two of them). You must write your implementation file using a linked list instead of an array as we did in class. You can even make the list doubly linked which means that in addition to have a next pointer, every node also has a previous pointer so that you can traverse the list in either direction.