python是什么 python中如何计算列表中元素的个数?
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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