两遍循环，第一遍检测AAA型错误，第二遍检测AABB型错误

两遍循环，第一遍检测AAA型错误，第二遍检测AABB型错误：

import java.util.*;
public class Main {
    public static void main(String[] args) throws Exception{
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());
        while(N-- > 0){
            String str = sc.nextLine();
            StringBuilder s = new StringBuilder(str);
            for(int i = 0; i + 2 < s.length(); ++i){
                char a = s.charAt(i), b = s.charAt(i + 1), c = s.charAt(i + 2);
                if(a == b && b == c) s.deleteCharAt(i--);
            }
            for(int i = 0; i + 3 < s.length(); ++i){
                char a = s.charAt(i), b = s.charAt(i + 1), c = s.charAt(i + 2), d = s.charAt(i + 3);
                if(a == b && c == d) s.deleteCharAt(i + 2);
            }
            System.out.println(s);
        }
    }
}