How much of the pattern fits

For every place i of the text, find how much of the pattern fits there: the largest k such that text[i:i + k] == pat[:k]. Return these numbers as a list, one per place of the text. An answer is 0 when the first letters differ, and can never be more than the letters left in the text.

fits("aabxaab", "aab")   # [3, 1, 0, 0, 3, 1, 0]
fits("xxaba", "abab")     # [0, 0, 3, 0, 1]
fits("ab", "abab")        # [2, 0]

Both strings have lower-case letters, and the pattern has at least one.

Limits

• The text has up to 500,000 letters and the pattern up to 100,000. The big tests have 3 seconds each.
• Comparing letter by letter at every place is too slow when the answers are long.