输入一字符串，各个子串之间按空白字符隔开，分别显式其中最长、最短子串，以及最大、最小字符用paython编写程序

string = input("请输入字符串：")

# 按空格分割字符串
substrings = string.split()

# 初始化最长和最短子串为第一个子串
longest_substring = substrings[0]
shortest_substring = substrings[0]

# 初始化最大和最小字符为第一个子串的第一个字符
max_char = substrings[0][0]
min_char = substrings[0][0]

# 遍历所有子串
for substring in substrings:
# 更新最长和最短子串
if len(substring) > len(longest_substring):
longest_substring = substring
if len(substring) < len(shortest_substring):
shortest_substring = substring

# 遍历子串中的所有字符
for char in substring:
# 更新最大和最小字符
if ord(char) > ord(max_char):
max_char = char
if ord(char) < ord(min_char):
min_char = char

# 输出结果
print("最长子串：", longest_substring)
print("最短子串：", shortest_substring)
print("最大字符：", max_char)
print("最小字符：", min_char)