leetcode 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   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". public class Solution {public static void main(String[] args) {String a = "atyrytbqweasd";String result = convert(a,3);System.out.println(result);}    public static String convert(String s, int numRows) {    if(numRows == 1) return s;//只有一行则直接返回    String a[] = new String[numRows];//建立字符串类型的数组，并初始化为空    for(int i = 0;i<numRows;i++){    a[i] = "";    }    int k = 0;    boolean flag = false;//用来判断数组递增或递减    String result = "";    for(int j = 0;j<s.length();j++){    a[k] = a[k]+s.charAt(j);    if(k == 0){//在第一个数组就递增，在最后一个数组就递减    flag = false;    }    if(k == numRows-1){    flag = true;    }    if(flag == false){    k++;    }else{    k--;    }    }    for(int i = 0;i<numRows;i++){//依次读三个数组得到结果    result = result+a[i];    }    return result;    }    }