Given string str of length N, the task is to find the minimum length to which the given string can be reduced to by replacing any pair of non-equal adjacent characters with a single character at most K times.
Input: str = “aabc”, K =1
Replace “bc” with a single character “d” and decrement K by 1.
Therefore, str modifies to “aad”.
Since K = 0, the minimized length of the string is 3.
Input: str= “aabc”, K = 2
Naive Approach: The simplest approach is to traverse the string K times and during each traversal, check if any pair of adjacent characters of the given string are distinct or not. If found to be true, then replace both the characters with a single character that is not equal to its adjacent characters. Finally, print the minimum length of the string.
Time Complexity: O(N * K)
Auxiliary Space: O(1)
Efficient Approach: To optimize the above approach, the idea is to traverse the given string and check if any pair of adjacent characters of the given string are distinct or not. If found to be true, then print the value of max(1, (N – K)). Otherwise, print N. Follow the steps below to solve the problem:
- Traverse the given string str and check if any pair of adjacent characters are distinct or not.
- If found to be true, then print max(1, (N – K)) as the required answer.
- Otherwise, print N as the required answer.
Below is the implementation of the above approach:
Time Complexity: O(N)
Auxiliary Space: O(1)
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