[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;
}
};