[Leetcode] (python): 115-distinct subsequences

Source of the topic:

https://leetcode.com/problems/distinct-subsequences/

Test Instructions Analysis:

Given the string s and T, determine how many t,t in S can be composed of s substrings.

Topic Ideas:

This is a dynamic planning issue. Set ANS[I][J] to the number of s[:i] t[:j]. Then the dynamic programming equation is, if s[i-1] = = T[j-1]: ans[i][j] = ans[i-1][j-1] + ans[i-1][j];else:ans[i][j] = Ans[i-1][j].

Code (Python):

　　

classsolution (object):defnumdistinct (self, S, T):""": Type S:str:type t:str:rtype:int"""M,n=Len (s), Len (t) ans= [[0 forIinchRange (n+1)] forIinchRange (m+1)]         forIinchRange (M + 1): ans[i][0]= 1 forIinchRange (1,m + 1):             forJinchRange (1,n + 1):                ifS[i-1] = = T[j-1]: ans[i][j]= Ans[i-1][j-1] + ans[i-1][j]Else: Ans[i][j]= Ans[i-1][j]returnAns[m][n]

View Code

[Leetcode] (python): 115-distinct subsequences