Distinct Subsequences
Given two strings s and t, return the number of distinct subsequences of s which equals t.
The test cases are generated so that the answer fits on a 32-bit signed integer.
Example 1
Input
s = "rabbbit", t = "rabbit"Output
3There are 3 distinct ways to delete characters from
s to form "rabbit".Example 2
Input
s = "babgbag", t = "bag"Output
5There are 5 distinct ways to delete characters from
s to form "bag".Constraints
- 1 <= s.length, t.length <= 1000
- s and t consist of English letters.