Hard · Backtracking

Decode Numbers

Given a string of digits, return every way to decode it into lowercase letters with the keys "1"→a through "26"→z (each key is one or two digits and none starts with 0), in any order — an empty list when no decoding exists.

Examples

Example 1

{
  "digits": "12"
}

Output: 2 decodings

Example 2

{
  "digits": "226"
}

Output: 3 decodings

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