Given a string containing lowercase English alphabets. The task is to find the minimum number of characters needed to be removed so that the remaining string contains at most 2 unique characters.
Note: The final string can have duplicate characters. The task is only to reduce the string with minimum deletions such that there can be a maximum of 2 unique characters in the resultant string.
Input: S = “geeksforgeeks”
After removing 7 characters the final string will be “geegee”
Input: S = “helloworld”
Approach: First count the occurrences of each character within the given string then just select two characters with maximum occurrence i.e. the two most frequently occurring characters in the string. And the result will be:
String length – (Occurrence of 1st most frequent character + Occurrence of 2nd most frequent character)
Below is the implementation of the above approach:
Time Complexity: O(N), where N is the length of the given String.
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- Minimum characters to be added at front to make string palindrome
- Minimum sum of squares of character counts in a given string after removing k characters
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