LeetCode:《Excel Sheet Column Number 》

编程思路：类似于26进制的转换

class Solution:    # @param s, a string    # @return an integer    def titleToNumber(self, s):        d = {'A':1, 'B':2, 'C':3, 'D':4, 'E':5, 'F':6, 'G':7, 'H':8, 'I':9,             'J':10, 'K':11, 'L':12, 'M':13, 'N':14, 'O':15, 'P':16, 'Q':17,             'R':18, 'S':19, 'T':20, 'U':21, 'V':22, 'W':23, 'X':24, 'Y':25, 'Z':26}        n = len(s)        num = 0        i = 0        while i < n:            # 使用切片获取每个字母            num = num + d[s[i:i+1]] * math.pow(26, n-1-i)            i = i + 1        return int(num)