题解 | #将单词均匀排列#

import java.util.*;
import java.util.stream.Collectors;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param words string字符串一维数组
     * @param maxWidth int整型
     * @return string字符串一维数组
     */
    public String[] arrangeWords (String[] words, int maxWidth) {
        // write code here
        List<String> res = new ArrayList<>();
        // 当前行数
        int curRows = 0;
        for (int i = 0; i < words.length;) {
            int curWords = 0;
            int curLength = 0;
            int index;
            StringBuilder sb = new StringBuilder();

            // 根据最大字符数maxWidth判断当前行具备多少个单词字符串
            // curLength：当前单词字符串加一个空格的长度
            // curWords：当前单词字符串的个数
            while (i + curWords < words.length) {
                curLength += words[i + curWords].length() + 1;
                curWords++;
                if (curLength > maxWidth + 1) {
                    curWords--;
                    curLength = curLength - words[i + curWords].length() - 1;
                    break;
                }
            }
            // 单词数组当前行涵盖最后一个单词所在的索引位置
            index = i + curWords - 1;

            // 当前行除字符外空格长度
            int spaceLength = maxWidth - curLength + curWords;

            // 最后一行处理
            if (i + curWords == words.length) {
                for (int j = i; j < i + curWords; j++) {
                    if (j != i + curWords - 1) {
                        sb.append(words[j] + " ");
                    } else {
                        sb.append(words[j]);
                    }
                }
                int remainder = maxWidth - sb.length();
                for (int k = 0; k < remainder; k++) {
                    sb.append(" ");
                }
            } else {
                for (int j = i; j < i + curWords; j++) {
                    sb.append(words[j]);
                    int avgSpaceLength = 0;
                    // 只有单个单词行处理
                    if (curWords == 1) {
                        avgSpaceLength = spaceLength;

                        // 添加空格
                        for (int m = 0; m < avgSpaceLength; m++) {
                            sb.append(" ");
                        }
                    } else {
                        avgSpaceLength = (int)(Math.ceil(spaceLength * 1.0 / (curWords - 1)));
                        if (j != i + curWords - 1) {
                            // 如果某一行的空格不能均匀分配，那么使行左侧的空格数多于右侧的空格数。
                            int last = spaceLength - avgSpaceLength * (curWords - 2);
                            if (j == i + curWords - 2 && last < avgSpaceLength) {
                                avgSpaceLength = last;
                            }

                            // 添加空格
                            for (int m = 0; m < avgSpaceLength; m++) {
                                sb.append(" ");
                            }
                        }
                    }
                }
            }
            i = index + 1;
            res.add(sb.toString());
        }
        String[] result = new String[res.size()];
        for (int i = 0; i < res.size(); i++) {
            result[i] = res.get(i);
        }
        return result;
    }
}