如何生成列表的所有排列，以及如何添加在任何排列中只能出现一次的字符串

def generate_permutations(lst):
    if len(lst) == 0:
        return [[]]
    
    permutations = []
    for i in range(len(lst)):
        rest = lst[:i] + lst[i+1:]
        sub_permutations = generate_permutations(rest)
        for p in sub_permutations:
            permutations.append([lst[i]] + p)
    
    return permutations

def generate_permutations_unique(lst):
    if len(lst) == 0:
        return [[]]
    
    permutations = []
    used = set()
    for i in range(len(lst)):
        if lst[i] in used:
            continue
        used.add(lst[i])
        rest = lst[:i] + lst[i+1:]
        sub_permutations = generate_permutations_unique(rest)
        for p in sub_permutations:
            permutations.append([lst[i]] + p)
    
    return permutations