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Decode String

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Description

https://leetcode.com/problems/decode-string/description/

Solution

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class Solution(object):
    def decodeString(self, s):
        """
        :type s: str
        :rtype: str
        """
        return self.decodeFromIndex(s, 0)[1]
    
    def decodeFromIndex(self, s, index):
        ret = ""
        traverse = index
        
        while traverse < len(s):
            ret_string = ""
            number_str = ""
            number = None
            number_flag = False 
            while traverse < len(s) and ( (s[traverse] >= 'a' and s[traverse] <= 'z') or (s[traverse] >= 'A' and s[traverse] <= 'Z') ):
                ret += s[traverse]
                traverse += 1
            while traverse < len(s) and s[traverse] >= '0' and s[traverse] <= '9':
                number_flag = True
                number_str += s[traverse]
                traverse += 1
            if number_flag:
                number = int(number_str)
            
            
            if traverse < len(s) and s[traverse] == '[':
                traverse += 1
                [traverse, ret_string] = self.decodeFromIndex(s, traverse)
                
            if number:
                for i in range(number):
                    ret += ret_string
            
            print(traverse, ret_string)
            
            
            if traverse < len(s) and s[traverse] == ']':
                traverse += 1
                break
        
        return (traverse, ret)