Problem Statement | | | A palindrome is a string that is the same whether it is read from left to right or from right to left.
Consider a string of length N which contains only uppercase letters. Write down all of its contiguous substrings of length M (a separate substring must be written down for each starting position, even if some of these substrings are the same strings). If at least K of the substrings you have written down are palindromes, we call the string palindromful.
Return the number of different palindromful strings of length N. | | | Definition | | | | Class: | PalindromfulString | | Method: | count | | Parameters: | int, int, int | | Returns: | long | | Method signature: | long count(int N, int M, int K) | | (be sure your method is public) |
| | | | | | Constraints | | - | N will be between 2 and 11, inclusive. | | - | M will be between 2 and N, inclusive. | | - | K will be between 0 and 11, inclusive. | | | Examples | | 0) | | | | | Returns: 26 | | For a string of length 2, the only substring of length 2 is the string itself. Therefore, in this case we need to count palindromes of length 2, which are "AA", "BB", ..., "ZZ". |
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| | 1) | | | | | Returns: 676 | | This time there can be no palindrome among the substrings, so any string of length 2 will do. |
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| | 2) | | | | | Returns: 1326 | | Either the first two or the last two characters of the string should be equal, with no restrictions on the remaining one. This gives us 2*26*26=1352 variants, of which 26 are strings consisting entirely of the same character and therefore duplicated. |
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| | 3) | | | | | Returns: 676 | | We're looking for palindromes of length 4. |
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| | 4) | | | | |
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