Alice and Bob are playing a game. Initially, Alice has a string word = "a"
.
You are given a positive integer k
. You are also given an integer array operations
, where operations[i]
represents the type of the ith
operation.
Now Bob will ask Alice to perform all operations in sequence:
operations[i] == 0
, append a copy of word
to itself.operations[i] == 1
, generate a new string by changing each character in word
to its next character in the English alphabet, and append it to the original word
. For example, performing the operation on "c"
generates "cd"
and performing the operation on "zb"
generates "zbac"
.Return the value of the kth
character in word
after performing all the operations.
Note that the character 'z'
can be changed to 'a'
in the second type of operation.
Example 1:
Input: k = 5, operations = [0,0,0]
Output: "a"
Explanation:
Initially, word == "a"
. Alice performs the three operations as follows:
"a"
to "a"
, word
becomes "aa"
."aa"
to "aa"
, word
becomes "aaaa"
."aaaa"
to "aaaa"
, word
becomes "aaaaaaaa"
.Example 2:
Input: k = 10, operations = [0,1,0,1]
Output: "b"
Explanation:
Initially, word == "a"
. Alice performs the four operations as follows:
"a"
to "a"
, word
becomes "aa"
."bb"
to "aa"
, word
becomes "aabb"
."aabb"
to "aabb"
, word
becomes "aabbaabb"
."bbccbbcc"
to "aabbaabb"
, word
becomes "aabbaabbbbccbbcc"
.
Constraints:
1 <= k <= 1014
1 <= operations.length <= 100
operations[i]
is either 0 or 1.word
has at least k
characters after all operations.