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41 lines
1.2 KiB
Python
41 lines
1.2 KiB
Python
"""
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https://en.wikipedia.org/wiki/String-searching_algorithm#Na%C3%AFve_string_search
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this algorithm tries to find the pattern from every position of
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the mainString if pattern is found from position i it add it to
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the answer and does the same for position i+1
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Complexity : O(n*m)
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n=length of main string
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m=length of pattern string
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"""
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def naive_pattern_search(s: str, pattern: str) -> list:
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"""
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>>> naive_pattern_search("ABAAABCDBBABCDDEBCABC", "ABC")
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[4, 10, 18]
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>>> naive_pattern_search("ABC", "ABAAABCDBBABCDDEBCABC")
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[]
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>>> naive_pattern_search("", "ABC")
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[]
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>>> naive_pattern_search("TEST", "TEST")
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[0]
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>>> naive_pattern_search("ABCDEGFTEST", "TEST")
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[7]
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"""
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pat_len = len(pattern)
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position = []
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for i in range(len(s) - pat_len + 1):
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match_found = True
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for j in range(pat_len):
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if s[i + j] != pattern[j]:
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match_found = False
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break
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if match_found:
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position.append(i)
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return position
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if __name__ == "__main__":
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assert naive_pattern_search("ABCDEFG", "DE") == [3]
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print(naive_pattern_search("ABAAABCDBBABCDDEBCABC", "ABC"))
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