Question

168. Excel Sheet Column Title

中文文档

Description

Given an integer columnNumber, return _its corresponding column title as it appears in an Excel sheet_.

For example:

A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28 
...

 

Example 1:

Input: columnNumber = 1
Output: "A"

Example 2:

Input: columnNumber = 28
Output: "AB"

Example 3:

Input: columnNumber = 701
Output: "ZY"

 

Constraints:

• 1 <= columnNumber <= 231 - 1

Solutions

Solution 1

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 {
  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();
  }
}

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('');
}

impl Solution {
  #[allow(dead_code)]
  pub fn convert_to_title(column_number: i32) -> String {
    let mut ret = String::from("");
    let mut column_number = column_number;

    while column_number > 0 {
      if column_number <= 26 {
        ret.push((('A' as u8) + (column_number as u8) - 1) as char);
        break;
      } else {
        let mut left = column_number % 26;
        left = if left == 0 { 26 } else { left };
        ret.push((('A' as u8) + (left as u8) - 1) as char);
        column_number = (column_number - 1) / 26;
      }
    }

    ret.chars().rev().collect()
  }
}

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());
  }
}