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68. 文本左右对齐

给定一个单词数组 words 和一个长度 maxWidth ,重新排版单词,使其成为每行恰好有 maxWidth 个字符,且左右两端对齐的文本。

你应该使用 “贪心算法” 来放置给定的单词;也就是说,尽可能多地往每行中放置单词。必要时可用空格 ' ' 填充,使得每行恰好有 maxWidth 个字符。

要求尽可能均匀分配单词间的空格数量。如果某一行单词间的空格不能均匀分配,则左侧放置的空格数要多于右侧的空格数。

文本的最后一行应为左对齐,且单词之间不插入额外的空格。

注意:

  • 单词是指由非空格字符组成的字符序列。

  • 每个单词的长度大于 0,小于等于 maxWidth

  • 输入单词数组 words 至少包含一个单词。

示例 1:

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

示例 2:

输入:words = ["What","must","be","acknowledgment","shall","be"], maxWidth = 16
输出:
[
  "What   must   be",
  "acknowledgment  ",
  "shall be        "
]
解释: 注意最后一行的格式应为 "shall be    " 而不是 "shall     be",
     因为最后一行应为左对齐,而不是左右两端对齐。
     第二行同样为左对齐,这是因为这行只包含一个单词。

示例 3:

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

提示:

  • 1 <= words.length <= 300

  • 1 <= words[i].length <= 20

  • words[i] 由小写英文字母和符号组成

  • 1 <= maxWidth <= 100

  • words[i].length <= maxWidth

思路分析

有思路,但是没有对思路进行分类。参考题解,分为“最后一行”、“一个单词一行”和“多个单词一行”来分别处理。

  • 一刷

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/**
 * @author D瓜哥 · https://www.diguage.com
 * @since 2025-06-23 16:26:29
 */
public List<String> fullJustify(String[] words, int maxWidth) {
  List<String> result = new ArrayList<>();
  int right = 0, length = words.length;
  while (true) {
    int left = right;
    int lengthSum = 0;
    while (right < length && lengthSum + words[right].length() + (right - left) <= maxWidth) {
      lengthSum += words[right++].length();
    }
    // 最后一行
    if (right == length) {
      StringBuilder sb = new StringBuilder();
      while (left < length) {
        sb.append(words[left]);
        if (left < length - 1) {
          sb.append(' ');
        }
        left++;
      }
      while (sb.length() < maxWidth) {
        sb.append(' ');
      }
      result.add(sb.toString());
      return result;
    }
    int wordCount = right - left;
    int spaceCount = maxWidth - lengthSum;
    if (wordCount == 1) {
      StringBuilder sb = new StringBuilder();
      sb.append(words[left]);
      while (sb.length() < maxWidth) {
        sb.append(' ');
      }
      result.add(sb.toString());
      continue;
    }
    int avgSpace = spaceCount / (wordCount - 1);
    int mod = spaceCount % (wordCount - 1);
    StringBuilder sb = new StringBuilder();
    while (left < right) {
      sb.append(words[left]);
      if (left < right - 1) {
        int spaces = avgSpace + (mod-- > 0 ? 1 : 0);
        while (spaces-- > 0) {
          sb.append(' ');
        }
      }
      left++;
    }
    result.add(sb.toString());
  }
}