Leetcode 992 Subarray with k different integers
sparshgarg23 opened this issue · 1 comments
sparshgarg23 commented
In the problem it is mentioned that the subarray doesn't have to be distinct.I recieved a problem in my coding interview shown below
https://leetcode.com/discuss/interview-question/278341/Uber-phone-interview-Number-of-distinct-subarrays-with-at-most-k-odd-elements/265140
After reading the problem description and the subarray with k different integers,can we extend it to take into consideration odd elements.I tried doing that but I am getting 0 as my answer.Any suggestions will be welcome
kamyu104 commented
- There are at most O(n^2) distinct subarrays if all elemtents are distinct odds and k is n, then the worst case of complexity would be at least O(n^2).
- Most solutions in your link are O(n^3), which are not really O(n) or O(n^2) as they claimed.
- Here I provide a simple and real O(n^2) solution which is extended from 992 Subarrays with K Different Integers as you wished:
# Time: O(n^2)
# Space: O(t), t is the size of trie
import collections
class Solution(object):
def distinctSubarraysWithAtMostKOddIntegers(self, A, K):
def countDistinct(A, left, right, trie): # Time: O(n), Space: O(t)
result = 0
for i in reversed(xrange(left, right+1)):
if A[i] not in trie:
result += 1
trie = trie[A[i]]
return result
_trie = lambda: collections.defaultdict(_trie)
trie = _trie()
result, left, count = 0, 0, 0
for right in xrange(len(A)):
count += A[right]%2
while count > K:
count -= A[left]%2
left += 1
result += countDistinct(A, left, right, trie)
return result
- Another solution may be like what zed_b and TheSithPadawan said in the link:
- Find all distinct subarrays by building suffix tree in O(n^2), which could be improved by Ukkonen's Algorithm in O(nlogd), where d is the number of distinct integers
- Traverse the suffix tree until all paths with at most k odd elements are visited in O(r)
- Time: O(nlogd + r), r is the number of the result, which is between O(1) ~ O(n^2), thus total time is at best Ω(nlogd), and at worst O(n^2)
- Space: O(nd)