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python是什么 python中如何计算列表中元素的个数?

浏览量:2615 时间:2021-03-11 01:27:37 作者:admin

python中如何计算列表中元素的个数?

描述len() 方法返回列表元素个数。语法len()方法语法:len(list)参数list -- 要计算元素个数的列表。返回值返回列表元素个数。实例以下实例展示了 len()函数的使用方法:#!/usr/bin/pythonlist1, list2 = [123, "xyz", "zara"], [456, "abc"]print "First list length : ", len(list1)print "Second list length : ", len(list2)以上实例输出结果如下:First list length : 3Second lsit length : 2

python text中按字典序排列最小的子序列?

class Solution(object):

def smallestSubsequence(self, text):

"""

:type text: str

:rtype: str

"""

stack = []

last_o = {}

considered = {}

for i in range(len(text)-1,-1,-1):

if text[i] not in last_o:

last_o[text[i]] = i

considered[text[i]] = False

print(last_o)

i = 0

while i < len(text):

print(stack,i,text[i])

if len(stack) == 0:

stack.append(text[i])

considered[text[i]] = True

i =1

elif stack[-1]>text[i] and considered[text[i]] == False:

if last_o[stack[-1]]>i:

considered[stack[-1]]=False

stack.pop()

else:

considered[text[i]] = True

stack.append(text[i])

i =1

elif stack[-1]<text[i] and considered[text[i]] == False:

stack.append(text[i])

considered[text[i]] = True

i =1

else:

i =1

return "".join(i for i in stack)

python是什么 python如何获取字典的长度 python字典统计平均分

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