Text Justification

最新推荐文章于 2020-09-03 19:05:51 发布

原创最新推荐文章于 2020-09-03 19:05:51 发布 · 446 阅读

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本文介绍了一个用于文本格式化的算法，该算法能够确保每行文本恰好包含指定数量的字符，并实现左右两端对齐的效果。通过贪婪策略填充单词，在必要时添加额外的空格，确保即使在单词间空格数不均匀的情况下也能保持美观的格式。

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 {
public:
	vector<string> fullJustify(vector<string> &words, int L) {
		if(words.size()==0 || L==0) return words;
		vector<string> vstrs;
		vector<string> res;
		int wordCount = 0;
		int len=0;
		int i=0;
		bool first = true;
		while(i<words.size() && len<=L){
			++wordCount;
			if(first){
				len+=words[i].size();
				first = false;
			}else{
				len+=words[i].size()+1;//加1个空格
			}
			if(len<=L){
				vstrs.push_back(words[i]);
			}
			if(len < L) ++i;
			else break;
		}
		if(i==words.size()){
			string line = connectToLine(vstrs,wordCount,len,L,true);
			res.push_back(line);
		}else if(len>=L){
			if(len > L){
				len = len - words[i].size()-1;
				wordCount -= 1;
			}else{
				i += 1;
			}
			string line = connectToLine(vstrs,wordCount,len,L,false);
			words.erase(words.begin(),words.begin()+i);
			res = fullJustify(words,L);
			res.insert(res.begin(),line);
		}
		return res;
	}
private:
	string connectToLine(vector<string> &vstrs,int wordCount,int len,int L,bool lastLine){
		string line;
		bool flag=true;
		int spaceNum=L-len;
		if(lastLine){
			for(size_t j=0;j<vstrs.size();++j){
				if(flag){
					line.append(vstrs[j]);
					flag = false;
				}else{
					line.append(" ");
					line.append(vstrs[j]);
				}
			}
			for(int j=0;j<spaceNum;++j)
				line.append(" ");
			return line;
		}
		flag = true;
		spaceNum=L-(len-(wordCount-1));
		int restNum=spaceNum;
		int space = 0;
		if(wordCount!=1){
			restNum= spaceNum%(wordCount-1);
			space = spaceNum/(wordCount-1);
		}
		for(size_t j=0;j<vstrs.size();++j){
			if(flag){
				line.append(vstrs[j]);
				flag = false;
			}else{
				for(int j=0;j<space;++j)
					line.append(" ");
				if(restNum){
					line.append(" ");
					restNum--;
				}
				line.append(vstrs[j]);
			}
		}
		while(restNum){
			line.append(" ");
			restNum--;
		}
		return line;
	}
};