2022-10-07 update: added "Decoded String at Index" (#128)

Author: fartem

Diff for: README.md

@@ -588,6 +588,7 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 863. All Nodes Distance K in Binary Tree                                            | [Link](https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree/)                                           | [Link](./src/main/java/com/smlnskgmail/jaman/leetcodejava/medium/AllNodesDistanceKInBinaryTree.java)                                   |
 | 865. Smallest Subtree with all the Deepest Nodes                                    | [Link](https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/)                                   | [Link](./src/main/java/com/smlnskgmail/jaman/leetcodejava/medium/SmallestSubtreeWithAllTheDeepestNodes.java)                           |
 | 869. Reordered Power of 2                                                           | [Link](https://leetcode.com/problems/reordered-power-of-2/)                                                          | [Link](./src/main/java/com/smlnskgmail/jaman/leetcodejava/medium/ReorderedPowerOf2.java)                                               |
+| 880. Decoded String at Index                                                        | [Link](https://leetcode.com/problems/decoded-string-at-index/)                                                       | [Link](./src/main/java/com/smlnskgmail/jaman/leetcodejava/medium/DecodedStringAtIndex.java)                                            |
 | 889. Construct Binary Tree from Preorder and Postorder Traversal                    | [Link](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal/)                   | [Link](./src/main/java/com/smlnskgmail/jaman/leetcodejava/medium/ConstructBinaryTreeFromPreorderAndPostorderTraversal.java)            |
 | 890. Find and Replace Pattern                                                       | [Link](https://leetcode.com/problems/find-and-replace-pattern/)                                                      | [Link](./src/main/java/com/smlnskgmail/jaman/leetcodejava/medium/FindAndReplacePattern.java)                                           |
 | 894. All Possible Full Binary Trees                                                 | [Link](https://leetcode.com/problems/all-possible-full-binary-trees/)                                                | [Link](./src/main/java/com/smlnskgmail/jaman/leetcodejava/medium/AllPossibleFullBinaryTrees.java)                                      |

Diff for: src/main/java/com/smlnskgmail/jaman/leetcodejava/medium/DecodedStringAtIndex.java

@@ -0,0 +1,40 @@
+package com.smlnskgmail.jaman.leetcodejava.medium;
+
+// https://leetcode.com/problems/decoded-string-at-index/
+public class DecodedStringAtIndex {
+
+    private final String s;
+    private int k;
+
+    public DecodedStringAtIndex(String s, int k) {
+        this.s = s;
+        this.k = k;
+    }
+
+    public String solution() {
+        long size = 0;
+        int n = s.length();
+        for (int i = 0; i < n; i++) {
+            char c = s.charAt(i);
+            if (Character.isDigit(c)) {
+                size *= c - '0';
+            } else {
+                size++;
+            }
+        }
+        for (int i = n - 1; i >= 0; i--) {
+            char c = s.charAt(i);
+            k %= size;
+            if (k == 0 && Character.isLetter(c)) {
+                return Character.toString(c);
+            }
+            if (Character.isDigit(c)) {
+                size /= c - '0';
+            } else {
+                size--;
+            }
+        }
+        throw null;
+    }
+
+}

Diff for: src/test/java/com/smlnskgmail/jaman/leetcodejava/medium/DecodedStringAtIndexTest.java

@@ -0,0 +1,17 @@
+package com.smlnskgmail.jaman.leetcodejava.medium;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class DecodedStringAtIndexTest {
+
+    @Test
+    public void defaultTest() {
+        assertEquals(
+                "o",
+                new DecodedStringAtIndex("leet2code3", 10).solution()
+        );
+    }
+
+}