68.Text Justification
===

###### tags: `Hard` `Array` `String`

[68. Text Justification](https://leetcode.com/problems/text-justification/)

### 題目描述

Given an array of strings `words` and a width `maxWidth`, format the text such that each line has exactly `maxWidth` characters and is fully (left and right) justified.

You should pack your words in a greedy approach; that is, pack as many words as you can in each line. Pad extra spaces `' '` when necessary so that each line has exactly `maxWidth` characters.

Extra spaces between words should be distributed as evenly as possible. If the number of spaces on a line does not divide evenly between words, the empty slots on the left will be assigned more spaces than the slots on the right.

For the last line of text, it should be left-justified, and no extra space is inserted between words.

**Note:**

* A word is defined as a character sequence consisting of non-space characters only.
* Each word's length is guaranteed to be greater than `0` and not exceed `maxWidth`.
* The input array `words` contains at least one word.

### 範例

**Example 1:**

Input: words = ["This", "is", "an", "example", "of", "text", "justification."], maxWidth = 16
Output:
[
   "This    is    an",
   "example  of text",
   "justification.  "
]

**Example 2:**

Input: words = ["What","must","be","acknowledgment","shall","be"], maxWidth = 16
Output:
[
  "What   must   be",
  "acknowledgment  ",
  "shall be        "
]
Explanation: Note that the last line is "shall be    " instead of "shall     be", because the last line must be left-justified instead of fully-justified.
Note that the second line is also left-justified because it contains only one word.

**Example 3:**

Input: words = ["Science","is","what","we","understand","well","enough","to","explain","to","a","computer.","Art","is","everything","else","we","do"], maxWidth = 20
Output:
[
  "Science  is  what we",
  "understand      well",
  "enough to explain to",
  "a  computer.  Art is",
  "everything  else  we",
  "do                  "
]

**Constraints**:

* 1 <= `words.length` <= 300
* 1 <= `words[i].length` <= 20
* `words[i]` consists of only English letters and symbols.
* 1 <= `maxWidth` <= 100
* `words[i].length` <= `maxWidth`

### 解答

#### TypeScript

function fullJustify(words: string[], maxWidth: number): string[] {
  const result: string[] = [];
  let lineWords: string[] = [];
  let lineLength = 0;

  for (const word of words) {
    if (lineLength + word.length + lineWords.length > maxWidth) {
      result.push(...distributeSpaces(lineWords, maxWidth));
      lineWords = [];
      lineLength = 0;
    }
    lineWords.push(word);
    lineLength += word.length;
  }

  // 最後一行
  const lastLine = lineWords.join(' ') + ' '.repeat(maxWidth - lineLength - lineWords.length + 1);
  result.push(lastLine);

  return result;
}

function distributeSpaces(words: string[], maxWidth: number): string[] {
  // 計算基本空格數量
  const totalWordsLength = words.join('').length;
  let totalSpaces = maxWidth - totalWordsLength;

  // 計算間隙數量
  const gaps = words.length - 1;

  // 如果只有一個字詞，則所有空格都放在字詞後面
  if (gaps === 0) return [words[0] + ' '.repeat(totalSpaces)];

  // 計算每個間隙的基本空格數量和剩餘的空格
  const spacesPerGap = Math.floor(totalSpaces / gaps);
  const extraSpaces = totalSpaces % gaps;

  // 分配空格
  let result = words[0];
  for (let i = 1; i < words.length; i++) {
    // 基本空格數量加上可能的額外空格
    let gap = ' '.repeat(spacesPerGap + (i <= extraSpaces ? 1 : 0));
    result += gap + words[i];
  }

  return [result];
}

> [name=sheep][time=Thur, 24 Aug 2023]

### Reference

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