[Python] O(N) and O(T) with explanation
\nTime Complexity: O(N)\nSpace Complexity: O(T)\n\n\n\nfrom collections import Counter\nclass Solution:\n    def minWindow(self, s: str, t: str) -> str:\n\t\t# 
```\nTime Complexity: O(N)\nSpace Complexity: O(T)\n```\n\n```\nfrom collections import Counter\nclass Solution:\n    def minWindow(self, s: str, t: str) -> str:\n\t\t# Count number of occurrences of each character from target string.\n        t=Counter(t)   \n\t\t\n        #This will store number of unique characters in target string e.g "aba": 2, "abc": 3\n\t\tcount=len(t)    \n\t\t\n\t\t# Sliding window initialization\n\t\ti, j=0, 0  \n\t\t\n\t\t# Minimum size of the window where all characters from target string are found\n        mini_window=float(\'inf\')  \n\t\t\n\t\t# Return answer\n        mini_word=""\n        \n        while j < len(s):\n\t\t\n\t\t\t# The following loop will run till we get all occourences of target characters in the window\n\t\t\t# size of s[i: j], this is indicated if the count hits 0.\n            while j < len(s) and count != 0:  \n                if s[j] in t:\n                    t[s[j]] -= 1\n                    if t[s[j]] == 0:\n                        count -= 1\n                j += 1\n            \n\t\t\t# Now since we have a window from s[i: j] containing all characters from target string.\n\t\t\t# We will try to reduce the string until one character goes missing\n\t\t\t# And concurrently store the minimum string containing all characters from traget string.\n            while i <= j and count==0:\n                if mini_window > j-i:\n                    mini_word=s[i: j]\n                    mini_window = j-i # j-i is minimum window size.\n\n                if s[i] in t:\n                    t[s[i]] += 1\n                    \n                    if t[s[i]] >=1:\n                        count += 1    \n                i += 1\n\t\t\n\t\t# Finally return the answer we received\n        return mini_word\n```\n\n**UPVOTE IF YOU LIKED THE EXPLANATION OR COMMENT THE EDIT IF ANY**
['Sliding Window', 'Python3']