3019. Number of Changing Keys

problem

solution

class Solution {
public:
    int countKeyChanges(string s) {
        int count=0;
        int n = s.size();
        for(int i=1;i<n;++i)
        {
            count+=(tolower(s[i-1]) !=tolower(s[i]));
        }
        
        return count;
    }
};

analysis

• time complexity O(n)
• space complexity O(1)