Ritual Algorithm Mathematics—Excel Table Column Names

Table of contents

Excel table column name

answer:

code:

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Excel table column name

168. Excel table column names - LeetCode

Given an integer columnNumber, return its corresponding column name in the Excel table.

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"
Example 4:

Input: columnNumber = 2147483647
Output: "FXSHRXW"
 

hint:

1 <= columnNumber <= 231 - 1

answer:

• It can be seen that it is a simulated 26-bit system, which is entered every 26 bits, but generally starts from 0,
• This question starts from 1, so the number should be reduced by one
• 

Hexadecimal conversion idea:

• Loop to perform % operation on number to get the last digit,
• Then perform / operation on number,
• Remove the acquired digits until number is 0

code:

class Solution {
    public String convertToTitle(int columnNumber) {
        //看出是模拟26进制，每26位进一次，但是一般是从0开始，
        //本题从1开始，所以数字要减一
        StringBuilder sb=new StringBuilder();
        while(columnNumber>0){
            columnNumber--;
            int temp=columnNumber%26;
            sb.append((char)('A'+temp));
            columnNumber/=26;
        }
        sb.reverse();
        return sb.toString();
    }
}