Text Justification 文本对齐 @LeetCode

快被这道题搞死了。。

根据这篇重写了 http://www.cnblogs.com/TenosDoIt/p/3475275.html

分析：这一题需要注意两个点，a、当该行只放一个单词时，空格全部在右边 b、最后一行中单词间只有一个空格，其余空格全部在右边。然后只要贪心选择，在一行中尽量放多的单词。

package Level4;

import java.util.ArrayList;

/**
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.

click to show corner cases.
 */
public class S68 {

	public static void main(String[] args) {
		 String[] words = {"This", "is", "an", "example", "of", "text", "justification."};
//		 String[] words = {""};
//		 String[] words = {"What","must","be","shall","be."};
//		String[] words = { "" };
		int L = 16;
		System.out.println(fullJustify(words, L));
	}

	
	public static ArrayList<String> fullJustify(String[] words, int L) {
		ArrayList<String> ret = new ArrayList<String>();
		int wordsLen = words.length;	// 单词数组的长度
		int curWordIdx = 0;		// 处理第i个单词
		while(curWordIdx < wordsLen){		// 处理完所有单词后退出
			int charLen = 0;  // 当前行累积的字符数量
			int probeWordIdx = curWordIdx;
			while(probeWordIdx<wordsLen && charLen+words[probeWordIdx].length()<=L){	// 贪婪加入尽可能多的单词
				charLen += ((words[probeWordIdx++]).length()+1);		// 累积单词长度和至少要有一个空格
			}
			if(probeWordIdx-curWordIdx == 1){		// tmpWordIdx-curWordIdx: 该行放入单词的数目，如果只有一个单词要特殊处理
				String tmp = words[curWordIdx];	// 唯一的那个单词
				tmp = addSpace(tmp, L-words[curWordIdx].length());	// 那个单词后面都接上空格
				ret.add(tmp);
				curWordIdx = probeWordIdx;		// 更新curWordIdx，因为已经处理好当前行了
				continue;
			}
			
			// tmpWordIdx-curWordIdx: 该行放入单词的数目，也就是紧接的空格的数量（因为每个单词后接一个空格）
			// wordCharLen：当前行所有由单词组成的字符数量（不包括空格）
			int wordCharLen = charLen - (probeWordIdx-curWordIdx);		
			//meanSpace: 平均每个单词后的空格,tmpWordIdx<wordsLen 表示不是最后一行
			int meanSpace = probeWordIdx<wordsLen ? (L-wordCharLen)/(probeWordIdx-curWordIdx-1) : 1;
			//leftSpace: 多余的空格
			int leftSpace = probeWordIdx<wordsLen ? (L-wordCharLen)%(probeWordIdx-curWordIdx-1) : L-wordCharLen-(probeWordIdx-curWordIdx-1);
			String tmp = new String();
			for(int k=curWordIdx; k<probeWordIdx-1; k++){	// 对当前行最后一个单词特殊处理
				tmp += words[k];
				tmp = addSpace(tmp, meanSpace);
				if(probeWordIdx<wordsLen && leftSpace>0){	// 因为居中对齐
					tmp += " ";
					leftSpace--;
				}
			}
			tmp += words[probeWordIdx-1];		// 处理当前行的最后一个单词
			if(leftSpace > 0){		// 因为左对齐，所以在最后补上剩下的空格
				tmp = addSpace(tmp, leftSpace);
			}
			ret.add(tmp);
			curWordIdx = probeWordIdx;		// 处理下一行的要处理的单词
		}
		return ret;
	}
	
	public static String addSpace(String s, int count){
		for(int i=1; i<=count; i++){
			s += " ";
		}
		return s;
	}
	
	// ============================================
	
	
	// Bad attempt!
//	public static ArrayList<String> fullJustify2(String[] words, int L) {
//		int letterCnt = 0;
//		int wordCnt = 0;
//		for (String s : words) {
//			letterCnt += s.length(); // 计算字符总数
//		}
//
//		ArrayList<String> ret = new ArrayList<String>();
//		// if(L != 1){
//		// cnt = cnt + cnt-1;
//		// }
//		// System.out.println(cnt);
//		// int lines = (int) Math.ceil(1.0*cnt/L);
//		// System.out.println(lines);
//
//		int curWord = 0;
//		int oldWord = 0;
//		int totalWords = words.length;
//		while (true) {
//			letterCnt = 0;
//			wordCnt = 0;
//			curWord = oldWord;
//			while (curWord < words.length) {
//				letterCnt += words[curWord].length() + 1;
//				if (letterCnt > L + 1) { // 超过长度限制
//					break;
//				}
//				wordCnt += words[curWord].length(); // 计算总共单词个数
//				curWord++;
//			}
//			curWord--;
//			String s = "";
//			// System.out.println(wordCnt);
//			int totalSpaces = L - wordCnt; // 空格总数
//			int perSpaces = 0; // 每行的空格数目s
//			// if(j-oldj != 0){
//			perSpaces = (int) Math.ceil(1.0 * (L - wordCnt)
//					/ ((curWord - oldWord + 1) - 1));
//			// }
//
//			if (totalWords <= 0) {
//				break;
//			}
//			// System.out.println("totalSpaces:"+totalSpaces);
//			// System.out.println("perSpaces:"+perSpaces);
//			for (int k = oldWord; k <= curWord; k++) {
//				s += words[k];
//				if (totalWords == L && k == oldWord && totalSpaces != 0) {
//					s += " ";
//					totalSpaces -= 1;
//				} else {
//					if (perSpaces <= totalSpaces) {
//						for (int m = 0; m < perSpaces; m++) {
//							s += " ";
//						}
//						totalSpaces -= perSpaces;
//					} else {
//						for (int m = 0; m < totalSpaces; m++) {
//							s += " ";
//						}
//						totalSpaces -= totalSpaces;
//					}
//				}
//			}
//
//			totalWords -= (curWord - oldWord + 1);
//
//			ret.add(s);
//			oldWord = curWord + 1;
//		}
//		return ret;
//	}

	

}