import java.util.ArrayList;
import java.util.List;

/**
 * @Author :田宇寒.
 * @Date :Created in 17:08 2021年6月2日
 * @Description:字符串Z字形输出
 * @Modified By:
 * @Version: 1.0$
 */
public class code6 {

 public static void main(String[] args) {
 Solution2 solution = new Solution2();
 System.out.println(solution.convert("AB", 1));
 }

 static class Solution {
 public String convert(String s, int numRows) {
 /**
 * create by: 田宇寒
 * description: 暴力算法使用二维字符数组 时间复杂度 O(n) 空间复杂度 O(n2)
 * create time: 10:01 2021年6月3日
 * @Param: s
 * @Param: numRows
 * @return java.lang.String
 */
 if (numRows == 1 || s.length() <= numRows) {
 return s;
 }
 char[] chars = s.toCharArray();
 int colums = (int) Math.ceil(Double.valueOf(chars.length) / Double.valueOf(numRows*2 -2)) * (numRows - 1);
 char[][] charArray = new char[numRows][colums];
 boolean rowAdd = true;
 int i = 0, j = 0;
 for (char aChar : chars) {
 if (rowAdd) {
 charArray[i][j] = aChar;
 if (i == numRows - 1) {
 rowAdd = false;
 --i;
 ++j;
 } else {
 ++i;
 }
 } else {
 charArray[i][j] = aChar;
 if (i == 0) {
 rowAdd = true;
 ++i;
 } else {
 ++j;
 --i;
 }
 }
 }
 StringBuilder stringBuilder = new StringBuilder();
 for (char[] chars1 : charArray) {
 stringBuilder.append(chars1);
 }
 return stringBuilder.toString().replace("\u0000","");
 }
 }

 static class Solution2 {
 public String convert(String s, int numRows) {
 /**
 * create by: 田宇寒
 * description: 按行排序 时间复杂度O(n) 空间复杂度O(n)
 * create time: 10:20 2021年6月3日
 * @Param: s
 * @Param: numRows
 * @return java.lang.String
 */
 if (s.length() == 1 || numRows == 1) {
 return s;
 }
 List<StringBuilder> list = new ArrayList<>(numRows);
 for (int i = 0 ; i < numRows; i++) {
 list.add(new StringBuilder());
 }
 char[] chars = s.toCharArray();
 int currentRow = 0;
 int flag = -1;
 for (char c : chars) {
 StringBuilder stringBuilder = list.get(currentRow);
 stringBuilder.append(c);
 if (currentRow == numRows - 1 || currentRow == 0) {
 flag = -flag;
 }
 currentRow += flag;
 }
 StringBuilder result = new StringBuilder();
 for (StringBuilder stringBuilder : list) {
 result.append(stringBuilder.toString());
 }
 return result.toString();
 }
 }
}