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
class Solution { public: string convertToTitle(int n) { string res; while(n){ int r = (n-1)%26; res.push_back(‘A‘ + r); n = (n-1)/26; } reverse(res.begin(),res.end()); return res; } };
原文：http://www.cnblogs.com/zengzy/p/5057848.html