Program to find number of sublists containing maximum and minimum after deleting only one element in Python

Python Server Side Programming Programming

Suppose we have a list of numbers called nums and we can delete at most one element in the list. We have to find the maximum number of sublists that contain both the maximum and minimum values of the resulting list.

So, if the input is like nums = [3, 2, 6, 2, 4, 10], then the output will be 8, as if we remove 10 we will get [3, 2, 6, 2, 4] and there are eight sublists where it contains both the max and the min −

[2, 6]
[6, 2]
[2, 6, 2]
[3, 2, 6]
[6, 2, 4]
[2, 6, 2, 4]
[3, 2, 6, 2]
[3, 2, 6, 2, 4].

To solve this, we will follow these steps −

Define a function check() . This will take lst
mn := minimum of lst, mx := maximum of lst
min_pos := null, max_pos := null
ret := 0
for each index i and value num in lst, do
- if num is same as mn, then
  - min_pos := i
- if num is same as mx, then
  - max_pos := i
- if min_pos is null or max_pos is null, then
  - go for next iteration
- ret := ret + minimum of min_pos and (max_pos + 1)
return ret
From the main method do the following −
if size of nums <= 1, then
- return size of nums
ret := check(nums)
for each rem_cand in [minimum of nums , maximum of nums ], do
- if occurrence of rem_cand is 1, then
  - idx := index of rem_cand in nums
  - ret := maximum of ret and check(nums[from index 0 to idx - 1] concatenate nums[from index idx + 1 to end]
return ret

Example

Let us see the following implementation to get a better understanding −

Live Demo

class Solution:
   def solve(self, nums):
      if len(nums) <= 1:
         return len(nums)
      def check(lst):
         mn, mx = min(lst), max(lst)
         min_pos, max_pos = None, None
         ret = 0
         for i, num in enumerate(lst):
            if num == mn:
               min_pos = i
            if num == mx:
               max_pos = i
            if min_pos is None or max_pos is None:
               continue
            ret += min(min_pos, max_pos) + 1
         return ret
      ret = check(nums)
      for rem_cand in [min(nums), max(nums)]:
         if nums.count(rem_cand) == 1:
            idx = nums.index(rem_cand)
            ret = max(ret, check(nums[:idx] + nums[idx + 1 :]))
      return ret
ob = Solution()
nums = [3, 2, 6, 2, 4, 10]
print(ob.solve(nums))

Input

[3, 2, 6, 2, 4, 10]

Output

Arnab Chakraborty

Updated on 23-Dec-2020 06:27:51

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