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Help!
I don’t understand why we add the index of the pattern to the index of the text for counting pattern matches. Can someone please walk me through the logic?
def pattern_search(text, pattern):
print("Input Text:", text, "Input Pattern:", pattern)
for index in range(len(text)):
print("Text Index:", index)
match_count = 0
for char in range(len(pattern)):
print("Pattern Index:", char)
if pattern[char] == text[index + char]:
print("Matching index found")
if pattern[char] == text[index + char]: <= this part
Super late, but basically you need it to make sure the correct index of the text is being checked. The char variables we get from range(len(pattern)) are indices of the pattern, not the text. If you just use the char to reference a text letter without adding index to it, you will only search the text using the pattern’s indices. The code will only keep checking the same indices at the beginning of the text.
For example, let’s say the first letter of the pattern, the letter at index 0, is at index 10 of the text. The if pattern[char] == text[index + char] will work out to if pattern[0] == text[10 + 0]. On the next iteration, it’ll check if the next letter of the pattern at index 1 matches the text at index 11: if pattern[1] == text[10 + 1].
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