Package g0801_0900.s0880_decoded_string_at_index

Class Solution

java.lang.Object

g0801_0900.s0880_decoded_string_at_index.Solution

public class Solution
extends Object

880 - Decoded String at Index.<p>Medium</p> <p>You are given an encoded string <code>s</code>. To decode the string to a tape, the encoded string is read one character at a time and the following steps are taken:</p> <ul> <li>If the character read is a letter, that letter is written onto the tape.</li> <li>If the character read is a digit <code>d</code>, the entire current tape is repeatedly written <code>d - 1</code> more times in total.</li> </ul> <p>Given an integer <code>k</code>, return <em>the</em> <code>k^th</code> <em>letter ( <strong>1-indexed)</strong> in the decoded string</em>.</p> <p><strong>Example 1:</strong></p> <p><strong>Input:</strong> s = &ldquo;leet2code3&rdquo;, k = 10</p> <p><strong>Output:</strong> &ldquo;o&rdquo;</p> <p><strong>Explanation:</strong> The decoded string is &ldquo;leetleetcodeleetleetcodeleetleetcode&rdquo;. The 10^th letter in the string is &ldquo;o&rdquo;.</p> <p><strong>Example 2:</strong></p> <p><strong>Input:</strong> s = &ldquo;ha22&rdquo;, k = 5</p> <p><strong>Output:</strong> &ldquo;h&rdquo;</p> <p><strong>Explanation:</strong> The decoded string is &ldquo;hahahaha&rdquo;. The 5^th letter is &ldquo;h&rdquo;.</p> <p><strong>Example 3:</strong></p> <p><strong>Input:</strong> s = &ldquo;a2345678999999999999999&rdquo;, k = 1</p> <p><strong>Output:</strong> &ldquo;a&rdquo;</p> <p><strong>Explanation:</strong> The decoded string is &ldquo;a&rdquo; repeated 8301530446056247680 times. The 1^st letter is &ldquo;a&rdquo;.</p> <p><strong>Constraints:</strong></p> <ul> <li><code>2 <= s.length <= 100</code></li> <li><code>s</code> consists of lowercase English letters and digits <code>2</code> through <code>9</code>.</li> <li><code>s</code> starts with a letter.</li> <li><code>1 <= k <= 10⁹</code></li> <li>It is guaranteed that <code>k</code> is less than or equal to the length of the decoded string.</li> <li>The decoded string is guaranteed to have less than <code>2⁶³</code> letters.</li> </ul>

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
String	decodeAtIndex(String s, int k)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

decodeAtIndex

public String decodeAtIndex(String s,
 int k)