168.Excel-Sheet-Column-Title

168. Excel Sheet Column Title

题目地址

https://leetcode.com/problems/excel-sheet-column-title/

题目描述

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 
    ...

Example 1:
Input: 1
Output: "A"

Example 2:
Input: 28
Output: "AB"

Example 3:
Input: 701
Output: "ZY"

代码

Approach 1:

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();
    }
}

Approach #2

public class Solution {
  public String convertToTitle(int n) {
      String res = "";
      while(n != 0) {
          char ch = (char)((n - 1) % 26 + 65);
          n = (n - 1) / 26;
          res = ch + res;
      }
      return res;
  }
}