168. Excel Sheet Column Title

class Solution:
    def convertToTitle(self, n):
        """
        :type n: int
        :rtype: str
        """
        s=''
        while n>26:
            yu=n%26
            if yu==0:
                n=n//26-1 
                s+='Z'
            else:
                n=
 
n//26
                s+=chr(64+yu)
        s+=chr(64+n)
        return s[::-1]

171. Excel Sheet Column Number

class Solution:
    def titleToNumber(self, s):
        """
        :type s: str
        :rtype: int
        """
        n=len(s)
        res=0
        for i in range(n-1,-1,-1):
            res+=
 
(ord(s[n-1-i])-64)*26**i
        return res