mediumStringsPattern: STRREV 1001
Reverse Character Groups Solution
Problem Statement
Given a string of digits and letters, reverse each group of 3 characters. If a group has less than 3 characters, reverse the entire string.
Examples
Example 1:
Input:abcdef
Output:cbafed
Explanation: Reversing each group of 3 characters: 'abc' becomes 'cba' and 'def' becomes 'fed', resulting in 'cbafed'
Example 2:
Input:abcdefghi
Output:cbadefihg
Explanation: Reversing each group of 3 characters: 'abc' becomes 'cba', 'def' becomes 'fed', and 'ghi' becomes 'ihg', resulting in 'cbadefihg'
Example 3:
Input:ab
Output:ba
Explanation: Since the label length is less than 3, the entire label is reversed, resulting in 'ba'
Constraints
- Input string should be a unique alphanumeric identifier.
- The length of the input string should be between 1 and 100.
Time: O(n) Space: O(n)
The optimal approach is to iterate over the string only once, and in each iteration, reverse the current 3-character group and add it to the result. This approach has a time complexity of O(n) since we only need to iterate over the string once.
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