[leetcode 168] Excel Sheet Column Title

Question:

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 

分析：

相当于用A~Z表示26进制数（以1开始），若n可以被26整除，则说明Tile的最后一个字母为Z，将n置为n/26，否则余数（1~15）对应的字母为‘A’+余数-1，将n置为(n-26)/26；

代码如下：

<span style="font-size:14px;">class Solution {public:    string convertToTitle(int n) {        string r = "" ;        char c;        int m = n;        if(n == 0)            return r;        while(m){            int tep = m % 26;            char p;            if(tep != 0){                p = 'A' + tep - 1;                r = p + r;                m /= 26;            }            else{                p = 'Z';                r = p + r;                m = (m-26) / 26;            }        }        return r;    }};</span>