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Program to find length of longest sublist with given condition in Python
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, as the sublist [6, 6, 4,4] is the longest sublist that holds the criteria as 2 * 4 > 6.
To solve this, we will follow these steps−
ret := 0
define two double ended queues minq and maxq
l := 0, r := 0
while r < size of nums, do
n := nums[r]
while minq and n < nums[last element of minq], do
delete last element from minq
insert r at the end of minq
while maxq 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
delete first element of minq
if maxq[0] is same as l, then
delete first element of maxq
l := l + 1
ret := maximum of ret and (r - l)
return ret
Let us see the following implementation to get better understanding −
Example
class Solution: def solve(self, nums): from collections import deque 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 ob = Solution() nums = [10, 2, 6, 6, 4, 4] print(ob.solve(nums))
Input
[10, 2, 6, 6, 4, 4]
Output
4
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