[LeetCode] Text Justification

最新推荐文章于 2020-06-10 05:27:24 发布

1.02^365的成长裂变

最新推荐文章于 2020-06-10 05:27:24 发布

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本文介绍了一种文本格式化算法，该算法能够确保每行文本恰好达到指定长度，并实现左右两端对齐的效果。通过贪婪填充尽可能多的单词，并在必要时均匀分布额外的空格，以确保每行达到规定的长度。

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[Problem]

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]

class Solution {
public:
    vector<string> fullJustify(vector<string> &words, int L) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
   
        vector<string> res;
        int len = 0, start = 0, end = 0;
        while(end < words.size()){
            // try to add a word
            if(start == end){
                len = words[end].length();
            }
            else{
                len = len + 1+ words[end].length();
            }
   
            // full
            if(len == L){
                // generate line
                string line = words[start];
                for(int i = start+1; i <= end; ++i){
                    line += " " + words[i];
                }
                res.push_back(line);
   
                // update end
                end++;
                start = end;
            }
            // over flow
            else if(len > L){
                if(end - start == 1){
                    string line = words[start] + string(L - words[start].length(), ' ');
                    res.push_back(line);
                }
                else{
                    // get words length
                    len = 0;
                    for(int i = start; i <= end-1; ++i){
                        len += words[i].length();
                    }
   
                    // number of spaces in this line
                    int space = L - len;
   
                    // number of spaces between two words
                    int average = space / (end - start - 1);
                    int more = space % (end - start - 1);
   
                    // generate line
                    string line = words[start];
                    for(int i = start+1; i <= end-1; ++i){
                        if(i - start <= more){
                            line += string(average+1, ' ') + words[i];
                        }
                        else{
                            line += string(average, ' ') + words[i];
                        }
                    }
                    res.push_back(line);
                }
                start = end;
            }
            else{
                end++;
            }
        }
   
        // be careful to add the last line
        if(end > 0 && start < words.size()){
            string line = words[start];
            for(int i = start+1; i < end; ++i){
                line += " " + words[i];
            }
   
            // fill spaces
            line += string(L - line.length(), ' ');
            res.push_back(line);
        }
   
        return res;
    }
};