6. ZigZag Conversion

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 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”.

思路来自于： http://www.cnblogs.com/TenosDoIt/p/3738693.html

public class Solution {    public String convert(String s, int numRows) {        if(numRows == 1)            return s;        int len = s.length(), k = 0, interval = (numRows<<1)-2;        char[] res = new char[len];        for(int j = 0; j < len ; j += interval)//处理第一行            res[k++] = s.charAt(j);        for(int i = 1; i < numRows-1; i++)//处理中间行        {            int inter = (i<<1);            for(int j = i; j < len; j += inter)            {                res[k++] = s.charAt(j);                inter = interval - inter;            }        }        for(int j = numRows-1; j < len ; j += interval)//处理最后一行            res[k++] = s.charAt(j);        return new String(res);    }}