ZigZag Conversion

问题来源：https://leetcode.com/problems/zigzag-conversion/

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

/**
 * 
 * <p>
 * ClassName ZigZagConversion
 * </p>
 * <p>
 * Description 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".
 * </p>
 * 
 * @author TKPad wangx89@126.com
 *         <p>
 *         Date 2015年3月26日 下午3:13:03
 *         </p>
 * @version V1.0.0
 *
 */
public class ZigZagConversion {
    // 每一行用一个链表来存储
    public String convert(String s, int nRows) {
        if(1==nRows){
            return s;
        }

        List<List<Character>> list = new ArrayList<List<Character>>();
        char[] charArray = s.toCharArray();
        for (int i = 0; i < nRows; i++) {
            List<Character> list_i = new ArrayList<Character>();
            list.add(list_i);
        }
        boolean flag = true;// true:表示count递增，false:表示count递减
        int count = 0;// 小标，count可以决定从List集合中取出第几个List集合
        for (int i = 0; i < charArray.length; i++) {
            list.get(count).add(charArray[i]);
            if (flag) {
                count++;
            } else {
                count--;
            }
            if (count == 0 || count == nRows - 1) {
                flag = !flag;// 将标识翻转
            }
        }
        String res = "";
        for (int i = 0; i < nRows; i++) {
            Iterator<Character> iterator = list.get(i).iterator();
            while (iterator.hasNext()) {
                res += iterator.next();
            }
        }
        return res;
    }

    // Wrong Answer
    // Input : ABC,2
    // Output : ABC
    // Expected : ACB
    // Wrong Answer
    // Input: "ABCDE", 4
    // Output: "ABECD"
    // Expected: "ABCED"
    public static void main(String[] args) {
        String convert = new ZigZagConversion().convert("AB", 1);
        System.out.println(convert);
    }
}