168. 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

想清楚问题的本质就好做了 其实是10进制转26进制

public String convertToTitle(int n) {
    StringBuilder result = new StringBuilder();

    while(n>0){
        n--;
        result.insert(0, (char)('A' + n % 26));
        n /= 26;
    }

    return result.toString();
}