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 ...
Examples:
Example 1:
Input: columnNumber = 1
Output: "A"
Example 2:
Input: columnNumber = 28
Output: "AB"
Example 3:
Input: columnNumber = 701
Output: "ZY"Solution in Python
Python
class Solution:
def convertToTitle(self, columnNumber: int) -> str:
result = [] # Initialize an empty list to store the characters of the resulting column title.
while columnNumber > 0:
columnNumber -= 1 # Adjust columnNumber to be 0-indexed.
remainder = columnNumber % 26 # Find the remainder when columnNumber is divided by 26.
result.append(chr(remainder + ord('A'))) # Convert the remainder to a corresponding letter and append to result.
columnNumber //= 26 # Update columnNumber for the next iteration.
result.reverse() # The result list is in reverse order, so reverse it to get the correct title.
return ''.join(result) # Join the list of characters into a string and return it.Detailed Explanation:
- Initialization:
- We initialize an empty list
resultto store the characters of the resulting column title.
- We initialize an empty list
- Loop until columnNumber is greater than 0:
- Adjust
columnNumberby subtracting 1. This adjustment is necessary because Excel columns are 1-indexed, but the 26 letters (A-Z) are 0-indexed in terms of remainder calculations.
- Adjust
- Finding the corresponding letter:
- Compute the remainder when
columnNumberis divided by 26. This remainder will determine the current letter. - Convert the remainder to the corresponding character by adding it to the ASCII value of ‘A’ (which is 65). Use
chr()to get the character and append it to theresultlist.
- Compute the remainder when
- Update columnNumber:
- Divide
columnNumberby 26 using integer division to update it for the next iteration of the loop.
- Divide
- Reverse and join:
- After exiting the loop, the
resultlist will contain the characters in reverse order (since we are appending the least significant character first). Therefore, reverse the list. - Join the characters in the list to form the final column title string and return it.
- After exiting the loop, the
This approach effectively converts the given integer to its corresponding Excel column title by simulating the manual process of determining the letters, handling the 26-based system properly.
Solution in Javascript
JavaScript
/**
* @param {number} columnNumber
* @return {string}
*/
var convertToTitle = function(columnNumber) {
let result = []; // Initialize an empty array to store the characters of the resulting column title.
while (columnNumber > 0) {
columnNumber--; // Adjust columnNumber to be 0-indexed.
let remainder = columnNumber % 26; // Find the remainder when columnNumber is divided by 26.
result.push(String.fromCharCode(remainder + 65)); // Convert the remainder to a corresponding letter and append to result.
columnNumber = Math.floor(columnNumber / 26); // Update columnNumber for the next iteration.
}
result.reverse(); // The result array is in reverse order, so reverse it to get the correct title.
return result.join(''); // Join the array of characters into a string and return it.
};Solution in Java
Java
class Solution {
public String convertToTitle(int columnNumber) {
StringBuilder result = new StringBuilder(); // Initialize a StringBuilder to store the characters of the resulting column title.
while (columnNumber > 0) {
columnNumber--; // Adjust columnNumber to be 0-indexed.
int remainder = columnNumber % 26; // Find the remainder when columnNumber is divided by 26.
result.append((char)(remainder + 'A')); // Convert the remainder to a corresponding letter and append to result.
columnNumber /= 26; // Update columnNumber for the next iteration.
}
result.reverse(); // The result is in reverse order, so reverse it to get the correct title.
return result.toString(); // Convert the StringBuilder to a string and return it.
}
}Solution in C#
C#
public class Solution {
public string ConvertToTitle(int columnNumber) {
StringBuilder result = new StringBuilder(); // Initialize a StringBuilder to store the characters of the resulting column title.
while (columnNumber > 0) {
columnNumber--; // Adjust columnNumber to be 0-indexed.
int remainder = columnNumber % 26; // Find the remainder when columnNumber is divided by 26.
result.Append((char)(remainder + 'A')); // Convert the remainder to a corresponding letter and append to result.
columnNumber /= 26; // Update columnNumber for the next iteration.
}
// The result is in reverse order, so reverse it to get the correct title.
char[] charArray = result.ToString().ToCharArray();
Array.Reverse(charArray);
return new string(charArray); // Convert the reversed char array to a string and return it.
}
}