作业题，写了Python才发现老师要我们写C++[捂脸]，谢谢楼下各位。代码块：

def can_form_palindrome(s1, s2):
    t = s1 + s2
    count = {}
    for char in t:
        count[char] = count.get(char, 0) + 1
    odd_count = sum(1 for k, v in count.items() if v % 2 != 0)
    return odd_count <= 1

def check():
    C = int(input())
    for _ in range(C):
        n, m = map(int, input().split())
        s1 = input()
        s2 = input()
        if can_form_palindrome(s1, s2):
            print("YES")
        else:
            print("NO")

check()