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14 changes: 7 additions & 7 deletions strings/knuth_morris_pratt.py
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
from __future__ import annotations


def kmp(pattern: str, text: str) -> bool:
def knuth_morris_pratt(pattern: str, text: str) -> int:
"""
The Knuth-Morris-Pratt Algorithm for finding a pattern within a piece of text
with complexity O(n + m)
Expand All @@ -24,7 +24,7 @@ def kmp(pattern: str, text: str) -> bool:
while i < len(text):
if pattern[j] == text[i]:
if j == (len(pattern) - 1):
return True
return i - j
j += 1

# if this is a prefix in our pattern
Expand All @@ -33,7 +33,7 @@ def kmp(pattern: str, text: str) -> bool:
j = failure[j - 1]
continue
i += 1
return False
return -1


def get_failure_array(pattern: str) -> list[int]:
Expand Down Expand Up @@ -61,22 +61,22 @@ def get_failure_array(pattern: str) -> list[int]:
pattern = "abc1abc12"
text1 = "alskfjaldsabc1abc1abc12k23adsfabcabc"
text2 = "alskfjaldsk23adsfabcabc"
assert kmp(pattern, text1) and not kmp(pattern, text2)
print(knuth_morris_pratt(pattern, text1), knuth_morris_pratt(pattern, text2))

# Test 2)
pattern = "ABABX"
text = "ABABZABABYABABX"
assert kmp(pattern, text)
print(knuth_morris_pratt(pattern, text))

# Test 3)
pattern = "AAAB"
text = "ABAAAAAB"
assert kmp(pattern, text)
print(knuth_morris_pratt(pattern, text))

# Test 4)
pattern = "abcdabcy"
text = "abcxabcdabxabcdabcdabcy"
assert kmp(pattern, text)
print(knuth_morris_pratt(pattern, text))

# Test 5)
pattern = "aabaabaaa"
Expand Down