三元运算符
- 为真时的结果 if 返回布尔值的判断条件 else 为假时的结果
a = 20
b = 30
print(a if a < b else b) # 20
print({True: a, False: b}[a < b]) # 20
print((b, a)[a < b]) # 20
a, b = 10, 20
print("Both a and b are equal" if a != b else (
"a is greater than b" if a > b else "b is greater than a")) # Both a and b are equal
print("a is greater than b" if a > b else "b is greater than a") # "b is greater than a"