Encode and Decode Strings

题目：http://www.voidcn.com/blog/qq508618087/article/p-5704907.html

// new solution: 10/3/2016
public class Codec {

    // Encodes a list of strings to a single string.
    public String encode(List<String> strs) {
        StringBuilder sb = new StringBuilder();
        for(String str : strs) {
            sb.append(str.length()).append("/").append(str);
        }
        return sb.toString();
    }

    // Decodes a single string to a list of strings.
    public List<String> decode(String s) {
        List<String> result = new ArrayList<String>();
        int i = 0;
        while(i < s.length()) {
            int slash = s.indexOf("/", i);
            int size = Integer.parseInt(s.substring(i, slash));
            String str = s.substring(slash+1, slash+1+size);
            result.add(str);
            i = slash + size + 1;
        }
        return result;
    }
}


public class EncodeAndDecode {
  
  public String encode(String[] strs) {   
    if(strs == null || strs.length == 0) {
      return "";
    }
    StringBuilder sb = new StringBuilder();
    sb.append(strs.length).append("#");     // 首先计算数组元素个数，用#分隔
    for(String str : strs) {
      int len = str == null ? 0 : str.length();
      sb.append(len).append("%");    // 然后计算数组里每个元素长度，用%分隔
    }
    for(String str : strs) {
      sb.append(str);   // 最后粘贴每个元素
    }
    return sb.toString();
  }
  
  public String[] decode(String str) {
    if(str == null || str.length() == 0) {
      return new String[0];
    }
    
    String[] arrayLen = str.split("#");    
    int arr_len = Integer.parseInt(arrayLen[0]);  // 首先得到数组长度
    
    str = str.substring(arrayLen[0].length()+1);  // 更新str
    String[] wordLen = str.split("%");     
    int[] word_len = new int[arr_len];   
    int total = 0;
    for(int i=0; i<arr_len; i++) {
      word_len[i] = Integer.parseInt(wordLen[i]);   // 然后得到每个元素长度
      total += word_len[i];   // 同时记录所有元素长度之后 方便下面更新str
    }
    
    str = str.substring(str.length()-total);   // 更新str
    String[] result = new String[arr_len];
    for(int i=0; i<arr_len; i++) {
      result[i] = str.substring(0, word_len[i]);   // 根据每个元素长度得到相应元素
      str = str.substring(word_len[i]);
    }
    return result;
  }
  
  public static void main(String[] args) {
    EncodeAndDecode solution = new EncodeAndDecode();
    String[] arr = {"abc%cde", "a#aa", "haha"};
    String encode = solution.encode(arr);
    String[] decode = solution.decode(encode);
    System.out.println(Arrays.toString(decode));
  }
}