Minimum Chnanges for Beautiful String

XXX.Minimum Changes to Make Adjacent Characters Equal

String

Problem Statement:

Given a string s consisting of lowercase English letters, determine the minimum number of changes needed to make every pair of adjacent characters equal. You can only modify one character at a time.

Algorithm:

1. Initialize a counter variable count to track the required changes.
2. Iterate through the string in steps of 2 (checking pairs).
3. If the two characters in the pair are different, increment the counter.
4. Return the final count as the minimum number of changes needed.

Complexity:

Time: O(n), where n is the length of the string, as we iterate through the string once. | Space: O(1), as no additional data structures are used.

Java Implementation:

public int minChanges(String s) {
    int count = 0; // Tracks the number of changes needed
    for (int i = 0; i < s.length() - 1; i += 2) {
        if (s.charAt(i) != s.charAt(i + 1)) // If adjacent characters differ
            count++; // Increment change count
    }
    return count; // Return the total changes required
}
                

Python Implementation:

def min_changes(s):
    count = 0 # Tracks the number of changes needed
    for i in range(0, len(s) - 1, 2):
        if s[i] != s[i + 1]: # If adjacent characters differ
            count += 1 # Increment change count
    return count # Return the total changes required
                

C++ Implementation:

int minChanges(string s) {
    int count = 0; // Tracks the number of changes needed
    for (int i = 0; i < s.length() - 1; i += 2) {
        if (s[i] != s[i + 1]) // If adjacent characters differ
            count++; // Increment change count
    }
    return count; // Return the total changes required
}