LeetCode OJ - ZigZag Conversation

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".

my answer：

public class Solution_6 {
    public String convert(String s, int numRows) {

    	if (numRows <=1 || s.length() == 0)
    		return s;

    	String result = "";
    	int len = s.length();

    	for (int x=0;x<numRows && x<len; x++){

    		int pos = x;
            //System.out.println(pos);
    		result += s.charAt(pos);
            //System.out.println(result + "lala");

    		for (int y=1;pos<len;y++){
    			if(x==0 || x==numRows-1){
    				pos += 2*(numRows-1);
    			}else{
                    System.out.println(pos);
    				if (y%2 == 1){
                        pos += 2*(numRows-1-x);
                    }
    					
    				else
                        //System.out.println(pos + "la");
    					pos +=2*x;
    			}
            if(pos<len){
                //System.out.println(pos);
                result+=s.charAt(pos);
                }          
    		}
    	}
    	return result;
    }

参考：http://wwwblogs/sanghai/p/3632528.html

改进：

public static String convert(String s, int numRows) {

        if (numRows <=1 || s.length() == 0)
            return s;

        String result = "";
        int len = s.length();
        int i = 0, j, gap = numRows-2;

        String[] temp = new String[numRows];
        for(int m=0;m<numRows;m++)
            temp[m]="";
        
        while(i<len){
            for(j=0;j<numRows && i<len;j++){
                //System.out.println(s.charAt(i));
                temp[j] += s.charAt(i++);
                
            }
            for(j=gap;i<len && j>0;j--)
                temp[j] += s.charAt(i++);
        }
        
        for(i=0;i<numRows;i++)
            result += temp[i];

        return result;
        
    }