Minimum Number of Changes to Make Binary String Beautiful

Leetcode Problem:

• Minimum Number of Changes to Make Binary String Beautiful

Summary

• The problem requires to find the minimum number of changes required to make a binary string beautiful
• A beautiful string is a string that can be partitioned into substrings with even length and only containing 1's or 0's.

Approach

• The approach is to iterate over the string in steps of 2 and count the number of pairs of characters that are not the same
• If the pair is not the same, it means that the string needs to be changed to make it beautiful, so we increment the result.

Complexity

• O(n/2) = O(n), where n is the length of the string.

Explanation

• The solution iterates over the string in steps of 2, which is because each pair of characters is considered together
• If the pair of characters is not the same, it means that the string needs to be changed to make it beautiful, so we increment the result
• The time complexity is O(n) because we are iterating over the string once.

Solution Code:

class Solution {
public:
    int minChanges(string s) {
        int res = 0;
        for(int i = 0 ; i < s.size(); i += 2){
            if ((s[i] == '0' && s[i+1] == '0') || (s[i] == '1' && s[i+1] == '1')){
                continue;
            }
            res++;
        }
        return res;
    }
};