A spam filter looks for a keyword hidden inside a message by spreading its letters out. A hidden copy is a choice of positions in text, in increasing order, whose letters spell keyword exactly. Two copies are different if they use a different set of positions.
Write countHiddenCopies(text, keyword) that returns the number of hidden copies, modulo 1000000007.
Input: text = "aab", keyword = "ab" Output: 2
The b can follow the first a or the second a.
Input: text = "abc", keyword = "d" Output: 0
The keyword's letter never appears.
1 <= text.length, keyword.length <= 1000Run tries your code on the examples. Submit runs every test, including hidden edge cases, and solves the problem when they all pass.
Ctrl + Enter runs, Ctrl + Shift + Enter submits (⌘ on a Mac).
I'm here to help with #568 Count Hidden Copies of a Keyword. I give hints, never the solution, so you get to solve it yourself. Ask for a hint, select code to ask about it, or press Ask Tuto why on a failing test.
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