@Xromeo

I saw your solution in JAVA but I have a thing to ask..in the below condition else if (k - changes >= 1 && s.charAt(left) != s.charAt(right)) {

                    chars[left] = '9';
                    chars[right] = '9';
                    changes++;
                }

In this condition, you are changing two characters but incrementing changes by 1. Why? For the string "092282" with k = 3, I debugged the code and in first loop the array was [2, 9, 2, 2, 9, 2] but in the above condition you are actually changing the values of both left and right index but incrementing the change by 1. I think it should be 2 . Am I mising something in the logic?