Python: Find smallest window that contains all characters of a given string
Python String: Exercise-75 with Solution
Write a Python program to find smallest window that contains all characters of a given string.
Sample Solution:
Python Code:
from collections import defaultdict
def find_sub_string(str):
str_len = len(str)
# Count all distinct characters.
dist_count_char = len(set([x for x in str]))
ctr, start_pos, start_pos_index, min_len = 0, 0, -1, 9999999999
curr_count = defaultdict(lambda: 0)
for i in range(str_len):
curr_count[str[i]] += 1
if curr_count[str[i]] == 1:
ctr += 1
if ctr == dist_count_char:
while curr_count[str[start_pos]] > 1:
if curr_count[str[start_pos]] > 1:
curr_count[str[start_pos]] -= 1
start_pos += 1
len_window = i - start_pos + 1
if min_len > len_window:
min_len = len_window
start_pos_index = start_pos
return str[start_pos_index: start_pos_index + min_len]
str1 = "asdaewsqgtwwsa"
print("Original Strings:\n",str1)
print("\nSmallest window that contains all characters of the said string:")
print(find_sub_string(str1))
Sample Output:
Original Strings: asdaewsqgtwwsa Smallest window that contains all characters of the said string: daewsqgt
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Previous: Write a Python program to find the minimum window in a given string which will contain all the characters of another given string.
Next: Write a Python program to count number of substrings from a given string of lowercase alphabets with exactly k distinct (given) characters.
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Python: Tips of the Day
Find current directory and file's directory:
To get the full path to the directory a Python file is contained in, write this in that file:
import os dir_path = os.path.dirname(os.path.realpath(__file__))
(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)
To get the current working directory use
import os cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
- The os and os.path modules.
- The __file__ constant
- os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
- os.path.dirname(path) (returns "the directory name of pathname path")
- os.getcwd() (returns "a string representing the current working directory")
- os.chdir(path) ("change the current working directory to path")
Ref: https://bit.ly/3fy0R6m
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