【LeetCode】6

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

P   A   H   N
A P L S I I G
Y   I   R

And then read line by line: "PAHNAPLSIIGYIR" 

Write the code that will take a string and make this conversion given a number of rows:

string convert(string text, int nRows);

convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".

Solution:原来是说：

1      7

2   6 8

3 5   9

4 

要搞成折线图,然后横着输出.建nRows个数组，将s一个一个装进下标为0，1....nRows-1....1,0的数组里，两层vector

class Solution {
public:
    string convert(string s, int nRows) {
       if(nRows==1)return s;
       vector<vector<char>> vec(nRows, vector<char>());
       
       int index=-1;
       int tag=1;
       for(int i=0;i<s.size();i++){
           index += tag;
           vec[index].push_back(s[i]);
           if(index==nRows-1)tag=-1;
           else{
               if(index==0)tag=1;
           }
       }
       string ret;
       for(int i=0;i<nRows;i++){
           for(int j=0;j<vec[i].size();j++){
               ret+=vec[i][j];
           }
       }
       return ret;
    }
};