Leetcode 394. Decode String
Decode a string containing nested repeat patterns of the form k[encoded_string], expanding each bracketed segment k times (k may be multi-digit) possibly with multiple nesting levels. Core challenge: parse and evaluate the nested structure correctly and efficiently (e.g., via stack or recursion) to produce the fully decoded string.
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Early August, 2026
Mid July, 2026
Let's assume we have encoded strings and we want to expand them. The encoding rule is k[char], k{char}, k(char) - will repeat the character k times. This format is guaranteed. However, cannot guarantee parentheses are valid: k[char}, or k}char{ Examples: 3}a}2[b] invalid case 3[a] = aaa 3{a}2[b] = aaabb 3(2[a]b) = aabaabaab 2[a] aa; aab 3 times -> aab aab aab 2[b]cd = bbcd 3(aab) aabaabaab
Mid June, 2026
k[ecnoded_string] - k is positive integer, decode string. and string appears exactly k time in decoded string
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