71.py

'''
 Given an absolute path for a file (Unix-style), simplify it.

 For example,
 path = "/home/", => "/home"
 path = "/a/./b/../../c/", => "/c"
'''

classSolution(object):
defsimplifyPath(self, path):
"""
 :type path: str
 :rtype: str
 """

result="/"
stack= []

index=0
whileindex<len(path):
ifpath[index] =='/':
index+=1
continue


curr_str=""
whileindex<len(path) andpath[index] !='/':
curr_str+=path[index]
index+=1

ifcurr_str=='.'orcurr_str=="":
index+=1
continue
elifcurr_str=="..":
ifstack:
stack.pop()
index+=1
else:
stack.append(curr_str)
index+=1

forindexinrange(len(stack)):
ifindex!=len(stack) -1:
result+=stack[index] +'/'
else:
result+=stack[index]

returnresult

# Time: O(N)
# Space: O(N)