leetcode 6. Z 字形变换

public class Solution {
public String convert(String s, int numRows) {
        if(numRows == 1){
            return s;
        }
        StringBuilder stringBuilder = new StringBuilder();
        int len = s.length();
        int t = 2 * numRows - 2;
        int l1 = numRows / t + 1;
        //第一行
        int i = 0;
        while(true){
            int i1 = t * i;
            if(i1 >= len){
                break;
            }
            stringBuilder.append(s.charAt(i1));
            i++;
        }
        //中间行
        for(int j = 2;j < numRows;j++){
            i = 0;
            while(true){
                int i2 = j - 1 + t * i;
                if(i2 >= len){
                    break;
                }
                stringBuilder.append(s.charAt(i2));
                int i1 = t - j + 1 + t * i;
                if(i1 >= len){
                    break;
                }
                stringBuilder.append(s.charAt(i1));
                i++;
            }
        }
        //最后一行
        i = 0;
        while(true){
            int i3 = numRows - 1 + t * i;
            if(i3 >= len){
                break;
            }
            stringBuilder.append(s.charAt(i3));
            i++;
        }
        return stringBuilder.toString();
    }
    public static void main(String[] args) {
        Solution solution = new Solution();
        String s = "PAYPALISHIRING";
        String ans = solution.convert(s,3);
        System.out.println(ans);
    }
}