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pre-commit-ci[bot] 2024-10-17 21:20:00 +00:00
parent 00b17c4c7c
commit 7fc42c79f0
1 changed files with 26 additions and 28 deletions
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54
strings/min_window_substring.py
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@ -14,24 +14,23 @@ def min_window(search_str: str, target_letters: str) -> str:
in the window, and shifting the start of the window right until the
window no longer contains every target character.
Time complexity: O(target_count + search_len) ->
The algorithm checks a dictionary at most twice for each character
Time complexity: O(target_count + search_len) ->
The algorithm checks a dictionary at most twice for each character
in search_str.
Space complexity: O(search_len) ->
The primary contributer to additional space is the building of a
Space complexity: O(search_len) ->
The primary contributer to additional space is the building of a
dictionary using the search string.
"""
target_count = len(target_letters)
search_len = len(search_str)
#Return if not possible due to string lengths.
if (search_len < target_count):
# Return if not possible due to string lengths.
if search_len < target_count:
return ""
#Build dictionary with counts for each letter in target_letters
# Build dictionary with counts for each letter in target_letters
char_dict = {}
for ch in target_letters:
if ch not in char_dict:
@ -39,49 +38,48 @@ def min_window(search_str: str, target_letters: str) -> str:
else:
char_dict[ch] += 1
#Initialize window
# Initialize window
window_start = 0
window_end = 0
exists = False
min_window_len = search_len + 1
#Start sliding window algorithm
while(window_end < search_len):
#Slide window end right until all search characters are contained
while(target_count > 0 and window_end < search_len):
# Start sliding window algorithm
while window_end < search_len:
# Slide window end right until all search characters are contained
while target_count > 0 and window_end < search_len:
cur = search_str[window_end]
if cur in char_dict:
char_dict[cur] -= 1
if (char_dict[cur] >= 0):
if char_dict[cur] >= 0:
target_count -= 1
window_end += 1
temp = window_end - window_start
#Check if window is the smallest found so far
if (target_count == 0 and temp < min_window_len):
min_window = [window_start,window_end]
# Check if window is the smallest found so far
if target_count == 0 and temp < min_window_len:
min_window = [window_start, window_end]
exists = True
min_window_len = temp
#Slide window start right until a search character exits the window
while(target_count == 0 and window_start < window_end):
# Slide window start right until a search character exits the window
while target_count == 0 and window_start < window_end:
cur = search_str[window_start]
window_start += 1
if cur in char_dict:
char_dict[cur] += 1
if (char_dict[cur] > 0):
if char_dict[cur] > 0:
break
temp = window_end - window_start + 1
#Check if window is the smallest found so far
if (temp < min_window_len and target_count == 0):
min_window = [window_start-1,window_end]
# Check if window is the smallest found so far
if temp < min_window_len and target_count == 0:
min_window = [window_start - 1, window_end]
min_window_len = temp
target_count = 1
if (exists):
return search_str[min_window[0]:min_window[1]]
if exists:
return search_str[min_window[0] : min_window[1]]
else:
return ""
return ""