Problem Statement |
| | Return how many strings containing length characters do not have the substring (quotes for clarity) "ab". The only characters allowed in the strings are 'a', 'b', and 'c'. A substring is any contiguous portion of a string. A substring may be empty, or the entire string. |
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Definition |
| | | Class: | BadSubstring | | Method: | howMany | | Parameters: | int | | Returns: | long | | Method signature: | long howMany(int length) | | (be sure your method is public) |
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Constraints |
| - | length will be between 0 and 44 inclusive. |
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Examples |
| 0) | |
| | | Returns: 1 | | The only string of length 0 is the empty string, and it doesn't have "ab" as a substring. |
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| 1) | |
| | | Returns: 21 | | There are 3*3*3=27 possible strings of length 3. 3 begin with ab, and 3 end with ab. The remaining 21 are all good. |
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| 2) | |
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