168.Excel Sheet Column Title
===

###### tags: `Easy` `String` `Math`

[168. Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title/)

### 題目描述

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
> ...

### 範例

**Example 1:**

Input: columnNumber = 1
Output: "A"

**Example 2:**

Input: columnNumber = 28
Output: "AB"

**Example 3:**

Input: columnNumber = 701
Output: "ZY"

**Constraints**:

* 1 <= `columnNumber` <= 2^31^ - 1

### 解答

#### TypeScript

function convertToTitle(columnNumber: number): string {
  const letters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  let result = '';

  while (columnNumber > 0) {
    columnNumber--; // 1-based to 0-based
    const rem = columnNumber % 26;
    result = letters[rem] + result;
    columnNumber = ~~(columnNumber / 26);
  }

  return result;
}

> [name=sheep][time=Tues, 22 Aug 2023]

#### javascript

function convertToTitle(columnNumber) {
  const alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  const title = [];

  while (columnNumber > 26) {
    columnNumber--;
    const remainder = columnNumber % 26;
    columnNumber = Math.floor(columnNumber / 26);
    title.push(alphabet[remainder]);
  }

  title.push(alphabet[columnNumber - 1]);

  return title.reverse().join('');
}

> 貼完看到上面的，被我弟虐爆，完全不知道我在寫三小。
> [name=Marsgoat][time=Tues, 22 Aug 2023]

### Reference

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