6 字符串Z字形变换

//按行分解即可得到相应内容
    //任何显示都可以使用矩阵点来量化
    public String convert(String s, int numRows) {
        if (numRows == 1) return s;
        StringBuilder ret = new StringBuilder();
        int n = s.length();
        int cycleLen = 2 * numRows - 2;
        //竖向
        for (int i = 0; i < numRows; i++) {
        	//横向
            for (int j = 0; j + i < n; j += cycleLen) {
                ret.append(s.charAt(j + i));
                if (i != 0 && i != numRows - 1 && j + cycleLen - i < n)
                    ret.append(s.charAt(j + cycleLen - i));
            }
        }
        return ret.toString();
    }