python基础语法

2020-09-24 | python | 295 字 | 2 分钟

列表推导式生成list

# in后面跟其他可迭代对象,如字符串
list_c = [7 * c for c in "python"]
print(list_c) 

# 带if条件语句的列表推导式
list_d = [d for d in range(6) if d % 2 != 0]
print(list_d) 

# 多个for循环
list_e = [(e, f * f) for e in range(3) for f in range(5, 15, 5)]
print(list_e) 

# 嵌套列表推导式,多个并列条件
list_g = [[x for x in range(g - 3, g)] for g in range(22) if g % 3 == 0 and g != 0]
print(list_g)

运行结果:

['ppppppp', 'yyyyyyy', 'ttttttt', 'hhhhhhh', 'ooooooo', 'nnnnnnn']
[1, 3, 5]
[(0, 25), (0, 100), (1, 25), (1, 100), (2, 25), (2, 100)]
[[0, 1, 2], [3, 4, 5], [6, 7, 8], [9, 10, 11], [12, 13, 14], [15, 16, 17], [18, 19, 20]]

参考：Python列表推导式_weixin_43790276的博客-CSDN博客

Dict操作

找出最大值

sampleDict = {'Ritika': 5, 'Sam': 27, 'John': 12, 'Sachin': 14, 'Mark': 19, 'Shaun' : 27}
itemMaxValue = max(sampleDict.items(), key=lambda x: x[1])
maxValue = max(sampleDict.values())
print(itemMaxValue[0], maxValue)

# output:
# Sam 27

Queue

层序遍历二叉树：

from queue import Queue
s = Solution()
q = Queue()
q.put(root)
while not q.empty():
    node = q.get()
    print(node.val)
    if node.left: q.put(node.left)
    if node.right: q.put(node.right)

python