[LeetCode] 168. Excel Sheet Column Title

Given a positive integer, return its corresponding column title as appear in an Excel sheet.

For example:

    1 -> A

    2 -> B

    3 -> C

    ...

    26 -> Z

    27 -> AA

    28 -> AB

    ...

Example 1:

Input: 1

Output: "A"

Example 2:

Input: 28

Output: "AB"

Example 3:

Input: 701

Output: "ZY"

这个题目实际上就想用26进制去将integer转换为string而已.可以看到如果是n%26, 如果是0, 那么就是Z, 否则的话就是chars[n%6], 并且之前的n/26要减一.

Code

1) 基本做法

class Solution:

    def convertToTitle(self, n):

        chars, rem, ans = 'Z' + string.ascii_uppercase, 1, ""

        while n > 0:

            rem, n = divmod(n, 26)

            ans += chars[n]

            if n == 0:

                rem -= 1

            n = rem

        return ans[::-1]

2) 利用chr(ord('A') + n) 去代替chars

class Solution:

    def converToTitle(self, n):

        ans = ""

        while n > 0:

            rem, n = divmod(n-1, 26)

            ans += chr(ord('A') + n)

            n = rem

        return ans[::-1]

3) 利用2) 的算法, 但是我们用recursive方式

class Solution:

    def converToTitle(self, n):

        return "" if n == 0 else self.converToTitle((n-1)/26) + chr(ord('A') + (n-1)%26)

巴特西

[LeetCode] 168. Excel Sheet Column Title_Easy tag: Math

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