Leet Code 68 Text Justification - Java

public class Solution {
public static List<String> fullJustify(String[] words, int maxWidth) {
List<String> result = new ArrayList<String>();
if (words == null || words.length == 0) {
return result;
}
int start = -1;
int length = 0;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < words.length; i++) {
start = i;
length = words[i].length();
while (i + 1 < words.length
&& length + 1 + words[i + 1].length() <= maxWidth) {
length += 1 + words[i + 1].length();
i++;
}
if (i < words.length - 1) {
if (start == i) {
result.add(justifyOneWord(words, maxWidth, start, sb));
} else {
result.add(justifyWords(words, maxWidth, length, start, i, sb));
}
} else {
result.add(justifyLastLine(words, maxWidth, start, i, sb));
}
}
return result;
}

private static String justifyOneWord(String[] words, int maxWidth, int i,
StringBuilder sb) {
sb.setLength(0);
sb.append(words[i]);
while (sb.length() < maxWidth) {
sb.append(" ");
}
return sb.toString();
}

private static String justifyWords(String[] words, int maxWidth, int length,
int start, int end, StringBuilder sb) {
sb.setLength(0);
int spaces = (maxWidth - length) / (end - start);
int left = (maxWidth - length) % (end - start);
for (int j = start; j <= end; j++) {
if (sb.length() > 0) {
sb.append(" ");
for (int k = 0; k < spaces; k++) {
sb.append(" ");
}
if (j - start <= left) {
sb.append(" ");
}
}
sb.append(words[j]);
}
return sb.toString();
}

private static String justifyLastLine(String[] words, int maxWidth,
int start, int end, StringBuilder sb) {
sb.setLength(0);
for (int j = start; j <= end; j++) {
if (sb.length() > 0) {
sb.append(" ");
}
sb.append(words[j]);
}
while (sb.length() < maxWidth) {
sb.append(" ");
}
return sb.toString();
}
}