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An encoded string s is given.  To find and write the decoded string to a tape, the encoded string is read one character at a time and the following steps are taken:

  • If the character read is a letter, that letter is written onto the tape.
  • If the character read is a digit (say d), the entire current tape is repeatedly written d-1 more times in total.

Now for some encoded string s, and an index k, find and return the k-th letter (1 indexed) in the decoded string.

 

Example 1:

Input: s = "leet2code3", k = 10
Output: "o"
Explanation: 
The decoded string is "leetleetcodeleetleetcodeleetleetcode".
The 10th letter in the string is "o".

Example 2:

Input: s = "ha22", k = 5
Output: "h"
Explanation: 
The decoded string is "hahahaha".  The 5th letter is "h".

Example 3:

Input: s = "a2345678999999999999999", k = 1
Output: "a"
Explanation: 
The decoded string is "a" repeated 8301530446056247680 times.  The 1st letter is "a".

 

Constraints:

  • 2 <= s.length <= 100
  • s will only contain lowercase letters and digits 2 through 9.
  • s starts with a letter.
  • 1 <= k <= 109
  • It's guaranteed that k is less than or equal to the length of the decoded string.
  • The decoded string is guaranteed to have less than 263 letters.

class Solution { public String decodeAtIndex(String s, int k) { } }