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| class Solution: def strStr(self, haystack: str, needle: str) -> int: next_list = self.get_next(needle)
i = 0 j = 0 while i < len(haystack) and j<len(needle): if haystack[i] == needle[j]: i+=1 j+=1 elif j>0: j = next_list[j-1] else: i+=1 if j == len(needle): return i-j return -1 def get_next(self,needle): next_list = [0] prefix_len = 0 i = 1 while i<len(needle): if needle[prefix_len] == needle[i]: prefix_len +=1 next_list.append(prefix_len) i+=1 else: if prefix_len == 0: next_list.append(0) i += 1 else: prefix_len = next_list[prefix_len-1] return next_list
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