# Encode and Decode Strings

Design an algorithm to encode**a list of strings**to**a string**. The encoded string is then sent over the network and is decoded back to the original list of strings.

## Example

Machine 1 (sender) has the function:

```
string encode(vector<string> strs) {
  // ... your code
  return encoded_string;
}
```

Machine 2 (receiver) has the function:

```
vector<string> decode(string s) {
  //... your code
  return strs;
}
```

So Machine 1 does:

```
string encoded_string = encode(strs);
```

and Machine 2 does:

```
vector<string> strs2 = decode(encoded_string);
```

`strs2`in Machine 2 should be the same as`strs`in Machine 1.

Implement the`encode`and`decode`methods.

## Note

list of string

直接加“/”分割

## Code

```java
public class Codec {

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

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

// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.decode(codec.encode(strs));
```
