public List<String> fullJustify(String[] words, int maxWidth) {

final List<String> res = new ArrayList<>();

int start = 0;

for (int i = 0, currRow = 0; i < words.length; i++) {

if (currRow + words[i].length() > maxWidth) {

currRow--;

res.add(formatRow(words, start, i, maxWidth - currRow));

start = i;

currRow = 0;

}

currRow += words[i].length() + 1;

}

final StringBuilder lastLine = new StringBuilder();

for (int i = start; i < words.length; i++) {

lastLine.append(words[i]);

if (i != words.length - 1) {

lastLine.append(' ');

}

}

final int length = lastLine.length();

for (int j = 0; j < maxWidth - length; j++) { lastLine.append(' '); }

res.add(lastLine.toString());

return res;

}

private static String formatRow(String[] words, int start, int end, int spaces) {

final StringBuilder sb = new StringBuilder();

if (end - start == 1) {

sb.append(words[start]);

for (int j = 0; j < spaces; j++) { sb.append(' '); }

return sb.toString();

}

final int space = spaces / (end - start - 1);

int remainder = spaces % (end - start - 1);

for (int i = start; i < end; i++) {

sb.append(words[i]);

if (i != end - 1) {

for (int j = 0; j <= space; j++) { sb.append(' '); }

if (remainder > 0) {

sb.append(' ');

remainder--;

}

}

}

return sb.toString();

}