Check if an Original String Exists Given Two Encoded Strings solution leetcode

Check if an Original String Exists Given Two Encoded Strings solution leetcode

An original string, consisting of lowercase English letters, can be encoded by the following steps:

  • Arbitrarily split it into a sequence of some number of non-empty substrings.
  • Arbitrarily choose some elements (possibly none) of the sequence, and replace each with its length (as a numeric string).
  • Concatenate the sequence as the encoded string.

For example, one way to encode an original string "abcdefghijklmnop" might be:

  • Split it as a sequence: ["ab", "cdefghijklmn", "o", "p"].
  • Choose the second and third elements to be replaced by their lengths, respectively. The sequence becomes ["ab", "12", "1", "p"].

    Check if an Original String Exists Given Two Encoded Strings solution leetcode

  • Concatenate the elements of the sequence to get the encoded string: "ab121p".

Given two encoded strings s1 and s2, consisting of lowercase English letters and digits 1-9 (inclusive), return true if there exists an original string that could be encoded as both s1 and s2. Otherwise, return false.

Note: The test cases are generated such that the number of consecutive digits in s1 and s2 does not exceed 3.

 

Example 1:

Check if an Original String Exists Given Two Encoded Strings solution leetcode

Input: s1 = "internationalization", s2 = "i18n"
Output: true
Explanation: It is possible that "internationalization" was the original string.
- "internationalization" 
  -> Split:       ["internationalization"]
  -> Do not replace any element
  -> Concatenate:  "internationalization", which is s1.
- "internationalization"
  -> Split:       ["i", "nternationalizatio", "n"]
  -> Replace:     ["i", "18",                 "n"]
  -> Concatenate:  "i18n", which is s2

Example 2:

Check if an Original String Exists Given Two Encoded Strings solution leetcode

Input: s1 = "l123e", s2 = "44"
Output: true
Explanation: It is possible that "leetcode" was the original string.
- "leetcode" 
  -> Split:      ["l", "e", "et", "cod", "e"]
  -> Replace:    ["l", "1", "2",  "3",   "e"]
  -> Concatenate: "l123e", which is s1.
- "leetcode" 
  -> Split:      ["leet", "code"]
  -> Replace:    ["4",    "4"]
  -> Concatenate: "44", which is s2.

Example 3:

Check if an Original String Exists Given Two Encoded Strings solution leetcode

Input: s1 = "a5b", s2 = "c5b"
Output: false
Explanation: It is impossible.
- The original string encoded as s1 must start with the letter 'a'.
- The original string encoded as s2 must start with the letter 'c'.

Example 4:

Check if an Original String Exists Given Two Encoded Strings solution leetcode

Input: s1 = "112s", s2 = "g841"
Output: true
Explanation: It is possible that "gaaaaaaaaaaaas" was the original string
- "gaaaaaaaaaaaas"
  -> Split:      ["g", "aaaaaaaaaaaa", "s"]
  -> Replace:    ["1", "12",           "s"]
  -> Concatenate: "112s", which is s1.
- "gaaaaaaaaaaaas"
  -> Split:      ["g", "aaaaaaaa", "aaaa", "s"]
  -> Replace:    ["g", "8",        "4",    "1"]
  -> Concatenate: "g841", which is s2.

Example 5:

Input: s1 = "ab", s2 = "a2"
Output: false
Explanation: It is impossible.
- The original string encoded as s1 has two letters.
- The original string encoded as s2 has three letters.

 

Constraints:

Check if an Original String Exists Given Two Encoded Strings solution leetcode

  • 1 <= s1.length, s2.length <= 40
  • s1 and s2 consist of digits 1-9 (inclusive), and lowercase English letters only.
  • The number of consecutive digits in s1 and s2 does not exceed 3.
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