[leetcode]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 

Credits:
Special thanks to @ifanchu for adding this problem and creating all test cases.

需要注意的地方就是A-Z是1-26

所以判断每一位的时候都需要n自减一下

class Solution {public:    string convertToTitle(int n) {        if(n<=0) return "";        string res="";        while(n){            n--;            char tmp=n%26+'A';            res=tmp+res;            n=n/26;        }        return res;    }};