Last active
August 29, 2015 14:25
-
-
Save oskar-j/8b99729826a1f4242e70 to your computer and use it in GitHub Desktop.
Find the monotonic pair whose indices are the furthest apart in Python
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
# method helps with fact that enumerate from reversed | |
# won't yield reversed indexes | |
def reverse_enum(L): | |
# guaranteed to NOT make any extra copy or search operations, O(1) | |
for index in reversed(xrange(len(L))): | |
yield index, L[index] | |
def solution(A): | |
top = list() | |
maximum = float("-inf") | |
# allocate temp list with O(n) time, put there maximal values descending | |
for item in reversed(A): | |
if (item > maximum): | |
maximum = item | |
top.insert(0, maximum) | |
best = 0 | |
cur_max_index = 0 | |
# iterate with O(n) time | |
for i, item in enumerate(A): | |
# simply calculate the distance, takes O(c*n) time, c between 0 and 1 | |
while(cur_max_index < len(top) and top[cur_max_index] >= item): | |
cur_max_index += 1 | |
if((cur_max_index - 1 - i) > best): | |
best = cur_max_index - 1 - i | |
return best | |
print solution([0]) | |
print solution([0, 0]) | |
print solution([1, 3, -3]) | |
print solution([5, 3, 6, 3, 4, 2]) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Inspired by: stackoverflow.com - monotonic-pair-codility