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Problems > Counting Embeddings

Counting Embeddings

Difficulty: 1800 3000 ms 128 MB

strings dp

Count how many distinct ways T occurs in S as a subsequence (positions distinguish occurrences), modulo 109+7.

Input: two lines: the text S, then the target T.

Output: the number of subsequence embeddings of T in S, mod 109+7.

Constraints:

  • 1 ≤ |S| ≤ 1000
  • 1 ≤ |T| ≤ 100
  • lowercase letters

Sample Tests

Input 1
rabbbit
rabbit
Output 1
3
Input 2
abc
abc
Output 2
1

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