有n个A，m个B，不能有三个相同的字母连续出现。任意写出来一个组合输出

# coding:utf-8
# n->A
# m->B
#输入n和m，构造一个n+m长度的字符串。正好有n个A，m个B。
# 不能有三个相同的字母连续出现。任意写出来一个组合输出
def construct(m, n, size):
    if max(m, n) <= min(m, n) * 2 + 2:
        dif = 0
        res = ""
        if m < n:
            dif = n - m - 2 if n - m >= 2 else n - m
            i = 1
            while i <= m:
                if i <= dif:
                    res += "AAB"
                else:
                    res += "AB"
                i += 1

            res += "AA" if n - m >= 2 else ""
            return res
        else:
            dif = m - n - 2 if m - n >= 2 else m - n
            i = 1
            while i <= n:
                if i <= dif:
                    res += "BBA"
                else:
                    res += "BA"
                i += 1
            res += "BB" if m - n >= 2 else ""
            return res

    else:
        return res


if __name__ == "__main__":
    m = 12
    n = 5
    ans = construct(m, n, 3)
    print(ans)