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# Expand the string according to the given conditions

• Difficulty Level : Medium
• Last Updated : 18 Aug, 2021

Given string str of the type “3(ab)4(cd)”, the task is to expand it to “abababcdcdcdcd” where integers are from the range [1, 9].
This problem was asked in ThoughtWorks interview held in October 2018.

Examples:

Input: str = “3(ab)4(cd)”
Output: abababcdcdcdcd
Input: str = “2(kl)3(ap)”
Output: klklapapap

Approach: We traverse through the string and wait for a numeric value, num to turn up at position i. As soon as it arrives, we check i + 1 for a ‘(‘. If it’s present, then the program enters into a loop to extract whatever is within ‘(‘ and ‘)’ and concatenate it to an empty string, temp. Later, another loop prints the generated string num number of times. Repeat these steps until the string finishes.

Below is the implementation of the approach:

## C++

 `// C++ implementation of the approach``#include``using` `namespace` `std;` `// Function to expand and print the given string``void` `expandString(string strin)``{``    ``string temp = ``""``;``    ``int` `j;` `    ``for` `(``int` `i = 0; i < strin.length(); i++)``    ``{``        ``if` `(strin[i] >= 0)``        ``{` `            ``// Subtract '0' to convert char to int``            ``int` `num = strin[i] - ``'0'``;``            ``if` `(strin[i + 1] == ``'('``)``            ``{` `                ``// Characters within brackets``                ``for` `(j = i + 1; strin[j] != ``')'``; j++)``                ``{``                    ``if` `((strin[j] >= ``'a'` `&& strin[j] <= ``'z'``) ||``                        ``(strin[j] >= ``'A'` `&& strin[j] <= ``'Z'``))``                    ``{``                        ``temp += strin[j];``                    ``}``                ``}` `                ``// Expanding``                ``for` `(``int` `k = 1; k <= num; k++)``                ``{``                    ``cout << (temp);``                ``}` `                ``// Reset the variables``                ``num = 0;``                ``temp = ``""``;` `                ``if` `(j < strin.length())``                ``{``                    ``i = j;``                ``}``            ``}``        ``}``    ``}``}` `// Driver code``int` `main()``{``    ``string strin = ``"3(ab)4(cd)"``;``    ``expandString(strin);``}` `// This code is contributed by Surendra_Gangwar`

## Java

 `// Java implementation of the approach``public` `class` `GFG {` `    ``// Function to expand and print the given string``    ``static` `void` `expandString(String strin)``    ``{``        ``String temp = ``""``;``        ``int` `j;` `        ``for` `(``int` `i = ``0``; i < strin.length(); i++) {``            ``if` `(strin.charAt(i) >= ``0``) {` `                ``// Subtract '0' to convert char to int``                ``int` `num = strin.charAt(i) - ``'0'``;``                ``if` `(strin.charAt(i + ``1``) == ``'('``) {` `                    ``// Characters within brackets``                    ``for` `(j = i + ``1``; strin.charAt(j) != ``')'``; j++) {``                        ``if` `((strin.charAt(j) >= ``'a'``                             ``&& strin.charAt(j) <= ``'z'``)``                            ``|| (strin.charAt(j) >= ``'A'``                                ``&& strin.charAt(j) <= ``'Z'``)) {``                            ``temp += strin.charAt(j);``                        ``}``                    ``}` `                    ``// Expanding``                    ``for` `(``int` `k = ``1``; k <= num; k++) {``                        ``System.out.print(temp);``                    ``}` `                    ``// Reset the variables``                    ``num = ``0``;``                    ``temp = ``""``;` `                    ``if` `(j < strin.length()) {``                        ``i = j;``                    ``}``                ``}``            ``}``        ``}``    ``}` `    ``// Driver code``    ``public` `static` `void` `main(String args[])``    ``{``        ``String strin = ``"3(ab)4(cd)"``;``        ``expandString(strin);``    ``}``}`

## Python3

 `# Python3 implementation of the approach` `# Function to expand and print the given string``def` `expandString(strin):``    ` `    ``temp ``=` `""``    ``j ``=` `0``    ``i ``=` `0``    ``while``(i < ``len``(strin)):``        ``if` `(strin[i] >``=` `"0"``):``            ` `            ``# Subtract '0' to convert char to int``            ``num ``=` `ord``(strin[i])``-``ord``(``"0"``)``            ``if` `(strin[i ``+` `1``] ``=``=` `'('``):``                ` `                ``# Characters within brackets``                ``j ``=` `i ``+` `1``                ``while``(strin[j] !``=` `')'``):``                    ``if` `((strin[j] >``=` `'a'` `and` `strin[j] <``=` `'z'``) ``or` `\``                        ``(strin[j] >``=` `'A'` `and` `strin[j] <``=` `'Z'``)):``                        ``temp ``+``=` `strin[j]``                    ``j ``+``=` `1``                    ` `                ``# Expanding``                ``for` `k ``in` `range``(``1``, num ``+` `1``):``                    ``print``(temp,end``=``"")``                    ` `                ``# Reset the variables``                ``num ``=` `0``                ``temp ``=` `""``                ``if` `(j < ``len``(strin)):``                    ``i ``=` `j``        ``i ``+``=` `1` `# Driver code``strin ``=` `"3(ab)4(cd)"``expandString(strin)` `# This code is contributed by shubhamsingh10`

## C#

 `// C# implementation of``// the above approach``using` `System;``class` `GFG{` `// Function to expand and``// print the given string``static` `void` `expandString(``string` `strin)``{``  ``string` `temp = ``""``;``  ``int` `j;` `  ``for` `(``int` `i = 0;``           ``i < strin.Length; i++)``  ``{``    ``if` `(strin[i] >= 0)``    ``{``      ``// Subtract '0' to``      ``// convert char to int``      ``int` `num = strin[i] - ``'0'``;``      ``if` `(strin[i + 1] == ``'('``)``      ``{``        ``// Characters within brackets``        ``for` `(j = i + 1;``             ``strin[j] != ``')'``; j++)``        ``{``          ``if` `((strin[j] >= ``'a'` `&&``               ``strin[j] <= ``'z'``) ||``              ``(strin[j] >= ``'A'` `&&``               ``strin[j] <= ``'Z'``))``          ``{``            ``temp += strin[j];``          ``}``        ``}` `        ``// Expanding``        ``for` `(``int` `k = 1; k <= num; k++)``        ``{``          ``Console.Write(temp);``        ``}` `        ``// Reset the variables``        ``num = 0;``        ``temp = ``""``;` `        ``if` `(j < strin.Length)``        ``{``          ``i = j;``        ``}``      ``}``    ``}``  ``}``}` `// Driver code``public` `static` `void` `Main(String [] args)``{``  ``string` `strin = ``"3(ab)4(cd)"``;``  ``expandString(strin);``}``}` `// This code is contributed by Chitranayal`

## Javascript

 ``
Output:
`abababcdcdcdcd`

Time Complexity: O(N*N)
Auxiliary Space: O(1)

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