63 lines
1.2 KiB
Markdown
63 lines
1.2 KiB
Markdown
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---
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layout: page
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title: Is Subsequence
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last_solved: 2020-07-08
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category: strings, 2ptr
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leetcode_url: https://leetcode.com/problems/is-subsequence
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status: Attempted
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---
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Problem
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-------
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```
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Given a string s and a string t, check if s is subsequence of t.
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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).
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Follow up:
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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?
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Example 1:
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Input: s = "abc", t = "ahbgdc"
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Output: true
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Example 2:
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Input: s = "axc", t = "ahbgdc"
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Output: false
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```
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Solution
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----------
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Gotchas:
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- 2 ptrs on string, have two conditions on while loop
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{% highlight python %}
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def isSubsequence(s, t):
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sp = 0
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tp = 0
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while sp<len(s) and tp<len(t):
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if s[sp]==t[tp]:
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sp+=1
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tp+=1
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continue
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else:
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tp+=1
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# reached end of s
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return sp==len(s)
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{% endhighlight %}
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![image1]()
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