[LeetCode] 168. Excel Sheet Column Title (Easy/Python)

Excel Sheet Column Title - LeetCode

Above is the link to the problem.

 

Problem

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 

Input: columnNumber = 701
Output: "ZY"

 

Analysis

1 to 26 are considered A to Z.

And columnNumber = 27 must print 'AA'

if we divide 27 by 26 and get the quotient and remainder, both are 1

Because of this, we print 27 to 'AA'

 

But there is one problem.

if we divide 26 by 26, then we get the quotient = 1 and remainder = 0.

then the program can't compute 0 here.

So error must occur.

 

We can solve this problem like this.

If the remainder gets 0, then the remainder be 26 and the quotient subtracts 1  

 

For example, if columnNumber is 26, the original result is quotient = 1 and remainder = 0,

but in this excel column, we think of this as quotient = 0 and remainder = 26

 

This is more example when columnNumber = 701

 

I solved this problem by the below code.

 

ASCII code : A=65 ~ Z=90 in the decimal number.

 

This code gets the top 0.78% of time efficiency and uses 13.9 MB of memory.