Excel Sheet

168. Excel Sheet Column Title



思路: 數字 轉 字母. reference map 0 ~ 25 對應到 A - Z 所以在處理n 的時候要 做 (n - 1) // 26.






26 => (26 - 1) % 26 = 25, ref[25] = 'Z'

class Solution(object):
    def convertToTitle(self, n):
        """
        :type n: int
        :rtype: str
        """
        dic = {}
        res = []
        for i in range(65, 91):
            dic[i - 65] = str(unichr(i))
        while n:
            res.insert(0, dic[(n-1) % 26])
            n = (n-1) // 26
        return "".join(res)

171. Excel Sheet Column Number

思路: 字母 轉 數字. 做26進位加法

class Solution(object):
    def titleToNumber(self, s):
        """
        :type s: str
        :rtype: int
        """
        ref = {}
        res = 0
        for i in range(26):
            ref[str(unichr(i + 65))] = i + 1
       
        s = list(s)
        multi = 0
        for i in range(len(s)-1, -1, -1):
            res += ref[s[i]] * 26 ** multi
            multi += 1
        return res