Text Justification

Change-Id: I258afaa8e7106642845c136a0d32d277282beca0

Author: applewjg

TextJustification.java

@@ -0,0 +1,64 @@
+/*
+ Author:     Andy, nkuwjg@gmail.com
+ Date:       Jan 29, 2015
+ Problem:    Text Justification
+ Difficulty: Hard
+ Source:     https://oj.leetcode.com/problems/text-justification/
+ Notes:
+ 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.
+ Corner Cases:
+ A line other than the last line might contain only one word. What should you do in this case?
+ In this case, that line should be left-justified.
+
+ Solution: ...
+ */
+
+public class Solution {
+    public List<String> fullJustify(String[] words, int L) {
+        List<String> res = new ArrayList<String>();
+        int i = 0, N = words.length;
+        while (i < N) {
+            int length = words[i].length();
+            int j = i + 1;
+            while (j < N && length + words[j].length() + (j-i) <= L) {
+                length += words[j++].length();
+            }
+            StringBuilder s = new StringBuilder(words[i]);
+            boolean isLastLine = (j==N);
+            boolean oneWord = (j == i + 1);
+            int average = (isLastLine || oneWord) ? 1 : (L-length)/(j-i-1);
+            int extra = (isLastLine || oneWord) ? 0 : (L-length)%(j-i-1);
+            for (int k = i + 1; k < j; ++k) {
+                char[] tmp = new char[extra>0?average+1:average];
+                Arrays.fill(tmp, ' ');
+                s.append(tmp);
+                s.append(words[k]);
+                extra--;
+            }
+            char[] tmp = new char[L - s.length()];
+            Arrays.fill(tmp, ' ');
+            s.append(tmp);
+            res.add(s.toString());
+            i = j;
+        }
+        return res;
+    }
+}