1003. Check If Word Is Valid After Substitutions
https://leetcode.com/problems/check-if-word-is-valid-after-substitutions
Description
Given a string s
, determine if it is valid.
A string s
is valid if, starting with an empty string t = ""
, you can transform t
into s
after performing the following operation any number of times:
Insert string
"abc"
into any position int
. More formally,t
becomestleft + "abc" + tright
, wheret == tleft + tright
. Note thattleft
andtright
may be empty.
Return true
if s
is a valid string, otherwise, return false
.
Example 1:
**Input:** s = "aabcbc"
**Output:** true
**Explanation:**
"" -> "abc" -> "aabcbc"
Thus, "aabcbc" is valid.
Example 2:
**Input:** s = "abcabcababcc"
**Output:** true
**Explanation:**
"" -> "abc" -> "abcabc" -> "abcabcabc" -> "abcabcababcc"
Thus, "abcabcababcc" is valid.
Example 3:
**Input:** s = "abccba"
**Output:** false
**Explanation:** It is impossible to get "abccba" using the operation.
Example 4:
**Input:** s = "cababc"
**Output:** false
**Explanation:** It is impossible to get "cababc" using the operation.
Constraints:
1 <= s.length <= 2 * 104
s
consists of letters'a'
,'b'
, and'c'
ac
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