動機

為什麼之前的commit這麼複雜

Problem

Given two strings s and t, return true if s is a subsequence of t, or false otherwise.

A subsequence of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., ace is a subsequence of abcde while aec is not).

 

Example 1:

Input: s = abc, t = ahbgdcOutput: true

Example 2:

Input: s = axc, t = ahbgdcOutput: false

 

Constraints:

  • 0 <= s.length <= 100
  • 0 <= t.length <= 104
  • s and t consist only of lowercase English letters.

 

Follow up: Suppose there are lots of incoming s, say s1, s2, ..., sk where k >= 109, and you want to check one by one to see if t has its subsequence. In this scenario, how would you change your code?

Sol

反正只要看handle中有沒有，那可以先把不必要的字去掉，之後一路比過去就好

class Solution:
    def isSubsequence(self, s: str, t: str) -> bool:
        s = [c for c in s]
        t = [c for c in t if c in s]
        i,j = [0,0]
        while j < len(t):
            if i < len(s):
                if s[i] == t[j]:
                    i += 1
            else:
                break
            j += 1
        return i >= len(s)