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Encode and Decode Strings

MediumP2Coding

Design a Codec that turns a list of strings into one string and back.

  • encode(strs) returns a single string that represents the list.
  • decode(s) takes the output of encode and returns the original list.

Strings may be empty and may contain any characters, including digits and #, so a plain separator is not safe. To make the output checkable, use this exact format: for every string write its length in decimal, then #, then the string itself, and concatenate the pieces. For example ["hello","world"] encodes to 5#hello5#world, and [""] encodes to 0#. An empty list encodes to the empty string.

Example 1

Input
["Codec","encode"] [[],[["hello","world"]]]
Output
[null,"5#hello5#world"]
Why
Each string is written as its length, a #, then its characters.

Example 2

Input
["Codec","decode"] [[],["5#hello5#world"]]
Output
[null,["hello","world"]]

Example 3

Input
["Codec","encode"] [[],[[""]]]
Output
[null,"0#"]
Why
An empty string still produces a length prefix.

Constraints

  • 0 <= strs.length <= 200
  • 0 <= strs[i].length <= 200
  • strs[i] may contain any ASCII characters.
  • decode is only called with strings produced by encode in the format above.

Hints

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