# meaning for list
s=[1,2,3,4]
c='abcd'
print(s[1:4])
print(s[1:3])
print(s[0:3])
print(s[0])
print(s[3])
print(c[1:4])
print(c[1:3])
print(c[0:3])
print(c[0])
print(c[3])

[2, 3, 4]
[2, 3]
[1, 2, 3]
1
4
bcd
bc
abc
a
d

class Solution:
    def romanToInt(self,s):
        translation={
            "I":1,
            "V":5,
            "X":10,
            "L":50,
            "C":100,
            "D":500,
            "M":1000
        }
        number=0
        s = s.replace("IV", "IIII").replace("IX", "VIIII")
        s = s.replace("XL", "XXXX").replace("XC", "LXXXX")
        s = s.replace("CD", "CCCC").replace("CM", "DCCCC")
        for char in s:
            number +=translation[char]
        return number
    

class Solution(object):
     def longestCommonPrefix(self, strs):

            if not strs:
                return ""
            shortest = min(strs,key=len)
            for i, ch in enumerate(shortest):
                for other in strs:
                    if other[i] != ch:
                        return shortest[:i]
            return shortest

class Solution:
    def isValid(self, s): 
        valid_brack = [('{', '}'), ('(', ')'), ('[', ']')]
        stack = []
        for c in s:
            if len(stack)>0 and (stack[-1], c) in valid_brack:
                stack.pop()
            else:
                stack.append(c)
        return len(stack)==0
    
solution = Solution()
s=")()"
result = solution.isValid(s)
print(result)  

class Solution(object):
    def strStr(self, haystack, needle):
        for i in range(len(haystack)):
            if haystack[i:i+len(needle)]==needle:
                return i
        return -1

# 倒序
def lengthofLastWords(s):
    length=0
    i=len(s)-1
    while i>=0 and s[i]=='':
        i-=1
    while i>=0 and s[i]!='':
        length+=1
        i-=1
    return length

s= "asvisl"
s_list=list(s)
c_list=list(reversed(s_list))
s=''.join(c_list)
print(s_list,c_list,s)

#result:['a', 's', 'v', 'i', 's', 'l'] ['l', 's', 'i', 'v', 's', 'a'] lsivsa

class Solution:
    def reverseVowels(self,s):
        s_list=list(s)
        c_list=list(reversed(s_list))
        s=''.join(c_list)
        return s

class Solution:
    def reverseVowels(self, s):
        Vowels=set('aeiouAEIOU')
        s=list(s)
        i,j=0,len(s)-1
        while i<j:
            if s[i] not in Vowels:
                i=i+1
            elif s[j] not in Vowels:
                j=j-1
            else: 
                s[i],s[j]=s[j],s[i]
                i=i+1
                j=j-1
        return ''.join(s)

class Solution(object):
    def validPalindrome(self, s):
        l,r=0,len(s)-1
        while l<r:
            if s[l]!=s[r]:
                return s[l+1:r+1] == s[l+1:r+1][::-1] or s[l:r] == s[l:r][::-1]
            l+=1
            r-=1
        return True