Given a string s and a number k. You need to tell count of distinct string of length k. s.t. k is a subset of s.↵
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Eg ↵
1. "aaabb" 2 => 4 (aa bb ab ba)↵
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2. "aabbcc" 2 => 9( aa ab ac ba bb bc ca cb cc)↵
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3. "abbcc" 2 => 8( same as #2 but aa can't be formed↵
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I can create a dp of state index and mask where mask is of base 26 and rest is straightforward.↵
Please help me in finding some combinatorics approach of solving it.
↵
Eg ↵
1. "aaabb" 2 => 4 (aa bb ab ba)↵
↵
2. "aabbcc" 2 => 9( aa ab ac ba bb bc ca cb cc)↵
↵
3. "abbcc" 2 => 8( same as #2 but aa can't be formed↵
↵
↵
I can create a dp of state index and mask where mask is of base 26 and rest is straightforward.↵
Please help me in finding some combinatorics approach of solving it.
