LeetCode 168 Excel Sheet Column Title (Excel Column to table Title)

LeetCode 168 Excel Sheet Column Title (Excel Column to table Title)
Translation

Given a positive integer, return it as the correct column title in the Excel table. Example: 1-> A 2-> B 3-> C... 26-> Z 27-> AA 28-> AB

Original

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 

Analysis

I seldom use Excel, so I don't fully understand the meaning of the question. I will first look at other people's solutions.

class Solution {public:    string convertToTitle(int n) {        if (n<=0) return "";        if (n<=26) return string(1, 'A' + n - 1);        return convertToTitle( n%26 ? n/26 : n/26-1 ) + convertToTitle( n%26 ? n%26 : 26 );    }};

Then we tried it in. Finally, I know what the question means ......

1 ... A*******26 ... Z27 ... AA*******52 ... AZ53 ... BA*******702 ... ZZ703 ... AAA

The recursion of the great god is actually 666, and the three-object operator is also used properly, so I have to admire it!

The above is

'A' + n - 1

Then I wrote the following code:

#include 
  
   using namespace std;string convertToTitle(int n) {    string title;    while (n > 0) {        title = (char)('A' + (--n) % 26) + title;        n /= 26;    }    return title;}int main() {    cout << convertToTitle(702);    return 0;}
  

Core code

title = (char)('A' + (--n) % 26) + title;

The solution is that it is used in habits

string title;title += "X";

This is all appended to the end. It may not be a habit to append the above, but it is no problem.

Because there is A starting A in it, so when we add it later, we need to reduce n by 1 at the beginning. Each time the last character is obtained, that is, every time a 26 character is removed, it is treated as a 26-digit system. In fact, it is consistent with the decimal system.

Code

class Solution {public:    string convertToTitle(int n) {        string res;        while (n > 0) {            res = (char)('A' + (--n) % 26) + res;            n /= 26;        }        return res;    }};