6. ZigZag Conversion

1.Question

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   NA P L S I I GY   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".

2.Code

class Solution {public:    string convert(string s, int numRows) {        if(numRows <= 1) return s;        string rs[numRows] = ""; //用numRows个string来保存每一行的字符串        for(int i = 0, j = 0, flag = 1, size = s.size(); i < size; i++)        {            rs[j] += s[i]; //j表示每一行            j += flag;   //flag的正负决定移动的方向是下一行还是上一行            if(j == 0 || j == numRows - 1) flag *= -1;        }        for(int i = 1; i < numRows; i++)  //把所有行拼接在一起            rs[0] += rs[i];        return rs[0];    }};

3.Note

a. 题目的意思是，把原字符串按Z字型重新排列，然后输出。