生成列表成员的所有组合，重复X次

def generate_combinations(lst, repeat):
    result = []
    backtrack(lst, repeat, [], result)
    return result

def backtrack(lst, repeat, path, result):
    if len(path) == repeat:
        result.append(path.copy())
        return
    for i in range(len(lst)):
        path.append(lst[i])
        backtrack(lst, repeat, path, result)
        path.pop()

# 示例用法
lst = [1, 2, 3]
repeat = 2
combinations = generate_combinations(lst, repeat)
print(combinations)