Syntax error Program to arrange cards so that they can be revealed in ascending order in Python

Program to arrange cards so that they can be revealed in ascending order in Python

Suppose we have a list of cards, and we want to order the cards in a way so that they are revealed in ascending order. As we know, the cards are revealed in this manner: 1. The top most card is removed and revealed and then next card is gone to the back. 2. Step 1 is repeated until there's no more cards. We have to find an ordering of the cards such that they are revealed in ascending order.

So, if the input is like cards = [1, 2, 3, 4, 5, 6, 7, 8], then the output will be [1, 5, 2, 7, 3, 6, 4, 8], as 1 is removed and 5 is moved to the back, current situation [2, 7, 3, 6, 4, 8, 5]. 2 is removed and 7 is moved to the back, current situation [3, 6, 4, 8, 5, 7] 3 is removed and 6 is moved to the back, current situation [4, 8, 5, 7, 6] 4 is removed and 8 is moved to the back, current situation [5, 7, 6, 8] 5 is removed and 7 is moved to the back, current situation [6, 8, 7]. 6 is removed and 8 is moved to the back, current situation [7, 8]. 7 is removed and there is only one card [8]. Then remove [8]

To solve this, we will follow these steps −

  • sort the list cards
  • idx:= a list with elements 0 to length of cards
  • order:= a new list
  • q:= a queue and insert elements of idx
  • while q is non-zero, do
    • delete element from left of q and insert into order
    • if q is non-zero, then
  • ans:= make a list of size cards, and fill with 0
  • for each element i from order and card from cards, do
    • ans[i]:= card
  • return ans

Let us see the following implementation to get better understanding −

Example

 Live Demo

from collections import deque
class Solution:
   def solve(self, cards):
      cards.sort()
      idx=[i for i in range(len(cards))]
      order=[]
      q=deque(idx)
      while q:
         order.append(q.popleft())
         if q: q.append(q.popleft())
      ans=[0 for _ in cards]
      for i,card in zip(order,cards):
         ans[i]=card
      return ans
ob = Solution()
print(ob.solve([1, 2, 3, 4, 5, 6, 7, 8]))

Input

[1, 2, 3, 4, 5, 6, 7, 8]

Output

[1, 5, 2, 7, 3, 6, 4, 8]
Updated on: 2020-10-05T12:33:31+05:30

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