如何删除字符串中的重复字符？

def remove_duplicates(s):
    return ''.join(set(s))

input_str = "hello world"
output_str = remove_duplicates(input_str)
print(output_str)

helo wrd

def remove_duplicates(s):
    seen = set()
    result = []
    for char in s:
        if char not in seen:
            seen.add(char)
            result.append(char)
    return ''.join(result)

input_str = "hello world"
output_str = remove_duplicates(input_str)
print(output_str)

helo wrd