Description
Domo is a train conductor, he wants to adjust the train he's driving.
There are five instructions below with the description:
1. AddFront num
Add a train carriage with the index num in front of the train.
2. AddBack num
Add a train carriage with the index num in back of the train.
3. Delete num
Delete all the train carriages with the index num from the train. (If the train has no any carriage with the index num, do nothing)
4. DeleteFront
Delete the first element of the train. (If the train is empty, do nothing)
5. Swap
Reverse all train carriages. (If the train is empty, do nothing)
For example:
AddFront 5 makes the train [4, 1] become [5, 4, 1].
AddBack 5 makes the train [4, 1] become [4, 1, 5].
Delete 5 makes the train [5, 4, 1, 5, 3] become [4, 1, 3].
DeleteFront make the train [1, 2, 3, 4] become [2, 3, 4].
Swap makes the train [2, 6, 3] become [3, 6, 2].
The train is empty in the beginning. Given a series of instructions, please print the index of train carriages after all instructions are executed.
This is a partial judge problem, you're asked to implement these 5 functions.
If you get a TLE:
Try to use the pointer head and back wisely, which can make the AddFront and AddBack instructions faster!
If you get an MLE:
Remember to free the nodes you've deleted!
Input
The input consists of multiple instructions (1 ≤ number of instructions ≤ 105)
the index of each instruction is a positive integer and not greater than 102.
Output
The output only consists of a line denoting the train carriage indices after all the instructions.
It's guaranteed that the output consists of at least one carriage.