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Java-based LeetCode algorithm problem solutions, regularly updated
880\. Decoded String at Index
Medium
You are given an encoded string `s`. To decode the 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 `d`, the entire current tape is repeatedly written `d - 1` more times in total.
Given an integer `k`, return _the_ kth
_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` consists of lowercase English letters and digits `2` through `9`.
* `s` starts with a letter.
* 1 <= k <= 109
* It is 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.