题目描述:

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

For example:

1
2
3
4
5
6
7
1 -> A
2 -> B
3 -> C
...
26 -> Z
27 -> AA
28 -> AB

按照26进制来处理, 不过由于是从1而不是0开始的, 所以要对Z单独处理.

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class Solution {
public:
    string convertToTitle(int n) {
        string ret;
        while(n > 0){
            if(n % 26 == 0) {
                ret.push_back('Z');
                n = n / 26 - 1;
            }
            else {
                ret.push_back((n % 26) + 'A' - 1);
                n /= 26;
            }
        }
        reverse(ret.begin(), ret.end());
        return ret;
    }
};