392. Is Subsequence-判断子序列

Given a string s and a string t, check if s is subsequence of t.

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

Follow up:
If there are lots of incoming S, say S1, S2, … , Sk where k >= 1B, and you want to check one by one to see if T has its subsequence. In this scenario, how would you change your code?

Credits:
Special thanks to @pbrother for adding this problem and creating all test cases.

Example 1:
Input: s = "abc", t = "ahbgdc"
Output: true

Example 2:
Input: s = "axc", t = "ahbgdc"
Output: false

Constraints:

• 0 <= s.length <= 100
• 0 <= t.length <= 10^4
• Both strings consists only of lowercase characters.

Solution in python:
1.Brute force

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