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Question

Formatted question description: https://leetcode.ca/all/168.html

 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
 ...

 Example 1:

 Input: 1
 Output: "A"

 Example 2:

 Input: 28
 Output: "AB"

 Example 3:

 Input: 701
 Output: "ZY"

Algorithm

For numbers less than 26, then we only need to take the remainder of 26, then subtract 1 and add the character A.

Code

• Java
• Python
• Go
• TypeScript
• C#

• 
  public class Excel_Sheet_Column_Title {
  
      class Solution {
          public String convertToTitle(int n) {
  
              if (n <= 0) {
                  return "";
              }
  
              StringBuilder sb = new StringBuilder();
              while (n > 0) {
  
                  // @note: key is, not n, but n-1
                  int remainder = (n - 1) % 26;
                  sb.insert(0, (char)('A' + remainder)); // @note: reverse order
  
                  n = (n - 1) / 26;
              }
  
              return sb.toString();
          }
      }
  }
  
  ############
  
  class Solution {
      public String convertToTitle(int columnNumber) {
          StringBuilder res = new StringBuilder();
          while (columnNumber != 0) {
              --columnNumber;
              res.append((char) ('A' + columnNumber % 26));
              columnNumber /= 26;
          }
          return res.reverse().toString();
      }
  }
  

• class Solution:
      def convertToTitle(self, columnNumber: int) -> str:
          res = []
          while columnNumber:
              columnNumber -= 1
              res.append(chr(ord('A') + columnNumber % 26))
              columnNumber //= 26
          return ''.join(res[::-1])
  
  ############
  
  class Solution(object):
    def convertToTitle(self, n):
      """
      :type n: int
      :rtype: str
      """
      ans = ""
      while n > 0:
        y = n % 26
        if y == 0:
          char = "Z"
          n -= 26
        else:
          char = chr(ord("A") + y - 1)
        ans += char
        n = n / 26
      return ans[::-1]
  
  

• func convertToTitle(columnNumber int) string {
  	res := []rune{}
  	for columnNumber != 0 {
  		columnNumber -= 1
  		res = append([]rune{rune(columnNumber%26 + int('A'))}, res...)
  		columnNumber /= 26
  	}
  	return string(res)
  }
  
  

• function convertToTitle(columnNumber: number): string {
      let res: string[] = [];
      while (columnNumber > 0) {
          --columnNumber;
          let num: number = columnNumber % 26;
          res.unshift(String.fromCharCode(num + 65));
          columnNumber = Math.floor(columnNumber / 26);
      }
      return res.join('');
  }
  
  

• public class Solution {
      public string ConvertToTitle(int columnNumber) {
          StringBuilder res = new StringBuilder();
          while (columnNumber != 0) {
              --columnNumber;
              res.Append((char) ('A' + columnNumber % 26));
              columnNumber /= 26;
          }
          return new string(res.ToString().Reverse().ToArray());
      }
  }
  

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