Akash and Akhil are playing a game. They have balls numbered from to . Akhil asks Akash to reverse the position of the balls, i.e., to change the order from say, 0,1,2,3 to 3,2,1,0. He further asks Akash to reverse the position of the balls times, each time starting from one position further to the right, till he reaches the last ball. So, Akash has to reverse the positions of the ball starting from position, then from position, then from position and so on. At the end of the game, Akhil will ask Akash the final position of any ball numbered . Akash will win the game, if he can answer. Help Akash.
The first line contains an integer , i.e., the number of the test cases.
The next lines will contain two integers and .
Print the final index of ball in the array.
2 3 1 5 2
For first test case, The rotation will be like this:
0 1 2 -> 2 1 0 -> 2 0 1 -> 2 0 1
So, Index of 1 will be 2.
Solution in Python
from collections import deque def reverse_index(n,k): for i in range(n): x = a.popleft() if i%2 else a.pop() if x==k: return i for _ in range(int(input())): n,k = map(int,input().split()) a = deque(range(n)) print(reverse_index(n,k))