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 

思路：Because any_pos_int mod 26 should return a number in the interval [0, 25], but what we want is a number in the interval [1, 26]. Thus we have to shift the digit leftward by 1 which meansn-1.

实现代码：

class Solution {
public:
    string convertToTitle(int n) {
    string res="";
    while(n>0){
        res=char('A'+(n-1)%26)+res;
        n=(n-1)/26;
    }
        return res;
    }
};

java版本：

public class Solution {

    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();
    }
}