# Program to find length of longest sublist with value range condition in Python

PythonServer Side ProgrammingProgramming

Suppose we have a list of numbers called nums, we have to find the length of the longest sublist where 2 * (minimum of sublist) > (maximum of sublist).

So, if the input is like nums = [10, 2, 6, 6, 4, 4], then the output will be 4, because the sublist [6, 6, 4, 4] is the longest sublist that meet the given criteria (2*4) > 6.

To solve this, we will follow these steps −

• ret := 0
• minq := an empty double ended queue
• maxq := an empty double ended queue
• l := 0
• r := 0
• while r < size of nums, do
• n := nums[r]
• while minq is not empty and n < nums[last element of minq], do
• delete last element from minq
• insert r at the end of minq
• while maxq is not empty and n > nums[last element of maxq], do
• delete last element from maxq
• insert r at the end of maxq
• r := r + 1
• while l < r and nums[minq[0]] * 2 <= nums[maxq[0]], do
• if minq[0] is same as l, then
• left left item from minq
• if maxq[0] is same as l, then
• delete last item of maxq
• l := l + 1
• ret := maximum of ret and (r - l)
• return ret

## Example

Let us see the following implementation to get better understanding −

from collections import deque
def solve(nums):
ret = 0
minq, maxq = deque(), deque()
l, r = 0, 0
while r < len(nums):
n = nums[r]
while minq and n < nums[minq[-1]]:
minq.pop()
minq.append(r)
while maxq and n > nums[maxq[-1]]:
maxq.pop()
maxq.append(r)
r += 1
while l < r and nums[minq[0]] * 2 <= nums[maxq[0]]:
if minq[0] == l:
minq.popleft()
if maxq[0] == l:
maxq.popleft()
l += 1
ret = max(ret, r - l)
return ret

nums = [10, 2, 6, 6, 4, 4]
print(solve(nums))

## Input

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

## Output

4
Published on 19-Oct-2021 10:49:30