Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).

Example:

Input: S = "ADOBECODEBANC", T = "ABC" Output: "BANC"

Note:

If there is no such window in S that covers all characters in T, return the empty string "".

If there is such window, you are guaranteed that there will always be only one unique minimum window in S.

Time: O(N)

class Solution: def minWindow(self, s: str, t: str) -> str: res = ‘‘ my_dict = {} for char in t: freq = my_dict.get(char, 0) my_dict[char] = freq + 1 count, start, end, min_len = len(my_dict), 0, 0, sys.maxsize res_end, res_start = 0, 0 while end != len(s): char = s[end] if char in my_dict: my_dict[char] -= 1 if my_dict[char] == 0: count -= 1 end += 1 while count == 0: start_char = s[start] if start_char in my_dict: my_dict[start_char] += 1 if my_dict[start_char] > 0: count += 1 if min_len > end - start: min_len = end - start res_end = end res_start = start start += 1 return s[res_start: res_end]

[LC] 76. Minimum Window Substring

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原文地址：https://www.cnblogs.com/xuanlu/p/11660721.html