- Difficulty: Easy
- Tags: LeetCode, Easy, Hash Table, String, leetcode-2325, O(n + m), O(1)
Problem
You are given the strings key
and message
, which represent a cipher key and a secret message, respectively. The steps to decode message
are as follows:
- Use the first appearance of all 26 lowercase English letters in
key
as the order of the substitution table. - Align the substitution table with the regular English alphabet.
- Each letter in
message
is then substituted using the table. - Spaces
' '
are transformed to themselves.
- For example, given
key = "happy boy"
(actual key would have at least one instance of each letter in the alphabet), we have the partial substitution table of ('h' -> 'a'
,'a' -> 'b'
,'p' -> 'c'
,'y' -> 'd'
,'b' -> 'e'
,'o' -> 'f'
).
Return the decoded message.
Example 1:
Input: key = "the quick brown fox jumps over the lazy dog", message = "vkbs bs t suepuv" Output: "this is a secret" Explanation: The diagram above shows the substitution table. It is obtained by taking the first appearance of each letter in "the quick brown fox jumps over the lazy dog".
Example 2:
Input: key = "eljuxhpwnyrdgtqkviszcfmabo", message = "zwx hnfx lqantp mnoeius ycgk vcnjrdb" Output: "the five boxing wizards jump quickly" Explanation: The diagram above shows the substitution table. It is obtained by taking the first appearance of each letter in "eljuxhpwnyrdgtqkviszcfmabo".
Constraints:
26 <= key.length <= 2000
key
consists of lowercase English letters and' '
.key
contains every letter in the English alphabet ('a'
to'z'
) at least once.1 <= message.length <= 2000
message
consists of lowercase English letters and' '
.