# Expand the string according to the given conditions

Given a 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

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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 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 `

Output:

```abababcdcdcdcd
```

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.

My Personal Notes arrow_drop_up Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.