Given an encoded string in form of `"ab[cd]{2}def"`\nYou have to return decoded string `"abcdcddef"`\n\nNotice that if there is a number inside curly braces, then it means preceding string in square brackets has to be repeated the same number of times. It becomes tricky where you have nested braces.\n\n**Example 1:**\n```\nInput: "ab[cd]{2}"\nOutput: "abcdcd"\n```\n\n**Example 2:**\n```\nInput: "def[ab[cd]{2}]{3}ghi"\nOutput: "defabcdcdabcdcdabcdcdghi"\n```\n\nSimilar problems:\n* https://leetcode.com/problems/decode-string

Given an encoded string in form of "ab[cd]{2}def"\nYou have to return decoded string "abcdcddef"\n\nNotice that if there is a number inside curly braces, then i