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Sort groups of numbers and characters separately in a String
• Last Updated : 26 Sep, 2019

Given a string str of alphanumeric characters, the task is to sort the similar group of consecutive characters separately and print the modified string i.e. all consecutive groups of digits and alphabetical characters will be sorted separately.

Examples:

Input: str = “121geeks21”
Output: 112eegks12
“121”, “geeks”, “21” are the valid groups
and they will be sorted separately.

Input: str = “cba321ab”
Output: abc123ab

Approach: Create a vector to store the starting indices of all the valid groups in the given string. Now, traverse the string character by character and if the current character is from a different group than the previous character then push the current index to the vector. After the string has been traversed completely, sort all the individual groups of substring of the given string using the vector updated earlier. Finally, print the modified string.

Below is the implementation of the above approach:

 `// C++ implementation of the approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function to return the modified string ` `string get_string(string str, ``int` `n) ` `{ ` ` `  `    ``// To store the previous character ` `    ``char` `prev = str; ` ` `  `    ``// To store the starting indices ` `    ``// of all the groups ` `    ``vector<``int``> result; ` ` `  `    ``// Starting index of the first group ` `    ``result.push_back(0); ` ` `  `    ``for` `(``int` `i = 1; i < n; i++) { ` ` `  `        ``// If the current character and the ` `        ``// previous character differ ` `        ``if` `(``isdigit``(str[i]) != ``isdigit``(prev)) { ` ` `  `            ``// Push the starting index ` `            ``// of the new group ` `            ``result.push_back(i); ` `        ``} ` ` `  `        ``// The current character now becomes previous ` `        ``prev = str[i]; ` `    ``} ` ` `  `    ``// Sort the first group ` `    ``sort(str.begin(), str.begin() + result); ` ` `  `    ``// Sort all the remaining groups ` `    ``for` `(``int` `i = 0; i < result.size() - 1; i++) { ` `        ``sort(str.begin() + result[i], ` `             ``str.begin() + result[i + 1]); ` `    ``} ` ` `  `    ``// Sort the last group ` `    ``sort(str.begin() + result[result.size() - 1], ` `         ``str.end()); ` ` `  `    ``// Return the modified string ` `    ``return` `str; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``string str = ``"121geeks21"``; ` `    ``int` `n = str.length(); ` ` `  `    ``cout << get_string(str, n); ` ` `  `    ``return` `0; ` `} `

Output:

```112eegks12
```

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