leetcode: 68. Text Justification [✗]

# Given an array of words and a length L, format the text such that each line has exactly L 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 L characters.
#
# Extra spaces between words should be distributed as evenly as possible. If the number of spaces on a line do 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.
#
# For example,
# words: ["This", "is", "an", "example", "of", "text", "justification."]
# L: 16.
#
# Return the formatted lines as:
# [
#     "This    is    an",
#     "example  of text",
#     "justification.  "
# ]
# Note: Each word is guaranteed not to exceed L in length.

class Solution(object):
    def fullJustify(self, words, maxWidth):
        """
        :type words: List[str]
        :type maxWidth: int
        :rtype: List[str]
        """
        lines = []
        i = 0
        while i<len(words):
            llen = 0  
            cur = i
            while i<len(words):
                llen += len(words[i])
                if llen>maxWidth:
                    llen -= len(words[i])
                    break
                llen+=1
                i+=1

            llen -=1
            if i != len(words):
                wordcnt = i-cur
                extra = maxWidth-llen                 
                if wordcnt>1:
                    spaces = extra/(wordcnt-1)
                    r = extra%(wordcnt-1)
                else:
                    spaces = extra
                    r = 0
            else:
                spaces = 0
                r = 0

            line = ""
            for word in words[cur:i]:
                line += word
                line += " "*(spaces+1)
                if r>0:
                    line += " "
                    r -= 1

            line = line[:maxWidth]
            if len(line)<maxWidth:
                line+=" "*(maxWidth-len(line))

            lines.append(line)

        return lines


# Time:  O(n)
# Space: O(k), k is maxWidth.
class Solution2(object):
    def fullJustify(self, words, maxWidth):
        """
        :type words: List[str]
        :type maxWidth: int
        :rtype: List[str]
        """
        def addSpaces(i, spaceCnt, maxWidth, is_last):
            if i < spaceCnt:
                return 1 if is_last else (maxWidth // spaceCnt) + int(i < maxWidth % spaceCnt)
            return 0

        def connect(words, maxWidth, begin, end, length, is_last):
            s = []  # The extra space O(k) is spent here.
            n = end - begin
            for i in range(n):
                s += words[begin + i],
                s += ' ' * addSpaces(i, n - 1, maxWidth - length, is_last),
            # For only one word in a line.
            line = "".join(s)
            if len(line) < maxWidth:
                line += ' ' * (maxWidth - len(line))
            return line

        res = []
        begin, length = 0, 0
        for i in range(len(words)):
            if length + len(words[i]) + (i - begin) > maxWidth:
                res += connect(words, maxWidth, begin, i, length, False),
                begin, length = i, 0
            length += len(words[i])

        # Last line.
        res += connect(words, maxWidth, begin, len(words), length, True),
        return res


if __name__ == "__main__":
    assert Solution().fullJustify(["This", "is", "an", "example", "of", "text", "justification."], 16) \
           == ['This    is    an', 'example  of text', 'justification.  ']