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.  "
]
思路: 每行能容纳的单词数是,单词长度+单词间的长度不超过maxWidth

注意数组越界,无限循环,以及除数为零

class Solution {
public:
    vector<string> fullJustify(vector<string>& words, int maxWidth) {
        int curLen = 0;
        int count = 0; //number of words in a line
        int spaceNum;
        int residue;
        int start = 0;
        string sLine = "";
        string sSpace = "";
        string sSpaceMore;
        vector<string> ret;
        
        for(int i = 0; i < words.size();){
            if(curLen + words[i].length() <= maxWidth){
                curLen += words[i].length();
                curLen++; //space
                count++;
                i++;
            }
            else{ //deal with space
                if(count == 1){ //保证除数!=0，所以这里要分开讨论
                    sLine += words[start++];
                    for(int j = curLen; j <= maxWidth; j++){
                        sLine += ' ';
                    }
                }
                else{
                    spaceNum = (maxWidth - curLen+1) / (count-1) + 1; //curLen-1 is the length of words with only one space; count-1 is the interval number
                    residue = (maxWidth - curLen+1) % (count-1);
                    for(int j = 0; j < spaceNum; j++){
                        sSpace += ' ';
                    }
                    sSpaceMore = sSpace + " ";
                    sLine += words[start++];
                    for(int j = 0; j < residue; j++){
                        sLine += sSpaceMore + words[start++];
                    }
                    for(int j = residue; j < count-1; j++ ){
                        sLine += sSpace + words[start++];
                    }
                }
                ret.push_back(sLine);
                sLine = "";
                sSpace = "";
                curLen = 0;
                count = 0;
                
            }
        }
        
        //last line
        if(start < words.size()){
            sLine += words[start++];
            for(int i = start; i < words.size(); i++){
                sLine += ' '+words[i];
            }
         
            for(int j = curLen; j <= maxWidth; j++){
                sLine += ' ';
            }
            ret.push_back(sLine);
        }
        return ret;
    }
};

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.  "
]