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feat: add solutions to lc problem: No.0271
No.0271.Encode and Decode Strings
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‎solution/0200-0299/0271.Encode and Decode Strings/README.md

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<!-- 这里可写通用的实现逻辑 -->
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**方法一：使用非 ASCII 码的分隔符**
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Python 中可以直接 `chr(257)` 作为字符串的分隔符，这样就可以实现字符串的编码和解码。
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时间复杂度 $O(n)$。
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**方法二：编码字符串长度**
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编码时，将字符串的长度转成固定 $4$ 位的字符串，加上字符串本身，依次拼接到结果字符串。
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解码时，先取前四位字符串，得到长度，再通过长度截取后面的字符串。依次截取，最终得到字符串列表。
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时间复杂度 $O(n)$。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Codec:
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def encode(self, strs: List[str]) -> str:
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"""Encodes a list of strings to a single string.
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"""
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return chr(257).join(strs)
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def decode(self, s: str) -> List[str]:
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"""Decodes a single string to a list of strings.
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"""
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return s.split(chr(257))
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# Your Codec object will be instantiated and called as such:
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# codec = Codec()
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# codec.decode(codec.encode(strs))
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```
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```python
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class Codec:
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def encode(self, strs: List[str]) -> str:
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"""Encodes a list of strings to a single string.
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"""
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ans = []
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for s in strs:
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ans.append('{:4}'.format(len(s)) + s)
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return ''.join(ans)
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def decode(self, s: str) -> List[str]:
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"""Decodes a single string to a list of strings.
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"""
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ans = []
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i, n = 0, len(s)
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while i < n:
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size = int(s[i: i + 4])
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i += 4
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ans.append(s[i: i + size])
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i += size
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return ans
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# Your Codec object will be instantiated and called as such:
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# codec = Codec()
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# codec.decode(codec.encode(strs))
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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public class Codec {
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// Encodes a list of strings to a single string.
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public String encode(List<String> strs) {
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StringBuilder ans = new StringBuilder();
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for (String s : strs) {
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ans.append((char) s.length()).append(s);
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}
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return ans.toString();
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}
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// Decodes a single string to a list of strings.
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public List<String> decode(String s) {
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List<String> ans = new ArrayList<>();
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int i = 0, n = s.length();
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while (i < n) {
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int size = s.charAt(i++);
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ans.add(s.substring(i, i + size));
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i += size;
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}
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return ans;
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}
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}
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// Your Codec object will be instantiated and called as such:
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// Codec codec = new Codec();
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// codec.decode(codec.encode(strs));
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```
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### **C++**
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```cpp
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class Codec {
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public:
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// Encodes a list of strings to a single string.
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string encode(vector<string>& strs) {
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string ans;
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for (string s : strs) {
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int size = s.size();
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ans += string((const char*)& size, sizeof(size));
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ans += s;
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}
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return ans;
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}
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// Decodes a single string to a list of strings.
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vector<string> decode(string s) {
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vector<string> ans;
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int i = 0, n = s.size();
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int size = 0;
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while (i < n) {
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memcpy(&size, s.data() + i, sizeof(size));
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i += sizeof(size);
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ans.push_back(s.substr(i, size));
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i += size;
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}
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return ans;
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}
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};
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// Your Codec object will be instantiated and called as such:
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// Codec codec;
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// codec.decode(codec.encode(strs));
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```
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### **Go**
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```go
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type Codec struct {
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}
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// Encodes a list of strings to a single string.
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func (codec *Codec) Encode(strs []string) string {
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ans := &bytes.Buffer{}
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for _, s := range strs {
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t := fmt.Sprintf("%04d", len(s))
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ans.WriteString(t)
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ans.WriteString(s)
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}
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return ans.String()
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}
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// Decodes a single string to a list of strings.
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func (codec *Codec) Decode(strs string) []string {
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ans := []string{}
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i, n := 0, len(strs)
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for i < n {
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t := strs[i : i+4]
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i += 4
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size, _ := strconv.Atoi(t)
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ans = append(ans, strs[i:i+size])
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i += size
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}
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return ans
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}
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// Your Codec object will be instantiated and called as such:
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// var codec Codec
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// codec.Decode(codec.Encode(strs));
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```
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### **...**

‎solution/0200-0299/0271.Encode and Decode Strings/README_EN.md

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@@ -84,13 +84,154 @@ String[] strs = decoder.decode(msg);
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### **Python3**
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```python
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class Codec:
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def encode(self, strs: List[str]) -> str:
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"""Encodes a list of strings to a single string.
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"""
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return chr(257).join(strs)
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def decode(self, s: str) -> List[str]:
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"""Decodes a single string to a list of strings.
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"""
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return s.split(chr(257))
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# Your Codec object will be instantiated and called as such:
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# codec = Codec()
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# codec.decode(codec.encode(strs))
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```
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```python
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class Codec:
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def encode(self, strs: List[str]) -> str:
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"""Encodes a list of strings to a single string.
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"""
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ans = []
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for s in strs:
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ans.append('{:4}'.format(len(s)) + s)
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return ''.join(ans)
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def decode(self, s: str) -> List[str]:
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"""Decodes a single string to a list of strings.
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"""
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ans = []
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i, n = 0, len(s)
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while i < n:
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size = int(s[i: i + 4])
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i += 4
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ans.append(s[i: i + size])
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i += size
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return ans
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# Your Codec object will be instantiated and called as such:
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# codec = Codec()
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# codec.decode(codec.encode(strs))
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```
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### **Java**
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```java
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public class Codec {
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// Encodes a list of strings to a single string.
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public String encode(List<String> strs) {
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StringBuilder ans = new StringBuilder();
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for (String s : strs) {
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ans.append((char) s.length()).append(s);
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}
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return ans.toString();
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}
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// Decodes a single string to a list of strings.
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public List<String> decode(String s) {
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List<String> ans = new ArrayList<>();
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int i = 0, n = s.length();
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while (i < n) {
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int size = s.charAt(i++);
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ans.add(s.substring(i, i + size));
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i += size;
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}
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return ans;
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}
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}
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// Your Codec object will be instantiated and called as such:
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// Codec codec = new Codec();
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// codec.decode(codec.encode(strs));
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```
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### **C++**
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```cpp
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class Codec {
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public:
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// Encodes a list of strings to a single string.
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string encode(vector<string>& strs) {
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string ans;
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for (string s : strs) {
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int size = s.size();
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ans += string((const char*)& size, sizeof(size));
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ans += s;
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}
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return ans;
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}
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// Decodes a single string to a list of strings.
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vector<string> decode(string s) {
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vector<string> ans;
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int i = 0, n = s.size();
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int size = 0;
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while (i < n) {
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memcpy(&size, s.data() + i, sizeof(size));
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i += sizeof(size);
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ans.push_back(s.substr(i, size));
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i += size;
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}
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return ans;
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}
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};
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// Your Codec object will be instantiated and called as such:
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// Codec codec;
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// codec.decode(codec.encode(strs));
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```
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### **Go**
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```go
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type Codec struct {
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}
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// Encodes a list of strings to a single string.
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func (codec *Codec) Encode(strs []string) string {
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ans := &bytes.Buffer{}
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for _, s := range strs {
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t := fmt.Sprintf("%04d", len(s))
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ans.WriteString(t)
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ans.WriteString(s)
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}
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return ans.String()
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}
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// Decodes a single string to a list of strings.
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func (codec *Codec) Decode(strs string) []string {
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ans := []string{}
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i, n := 0, len(strs)
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for i < n {
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t := strs[i : i+4]
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i += 4
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size, _ := strconv.Atoi(t)
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ans = append(ans, strs[i:i+size])
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i += size
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}
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return ans
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}
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// Your Codec object will be instantiated and called as such:
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// var codec Codec
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// codec.Decode(codec.Encode(strs));
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```
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### **...**

‎solution/0200-0299/0271.Encode and Decode Strings/Solution.cpp

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class Codec {
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public:
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// Encodes a list of strings to a single string.
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string encode(vector<string>& strs) {
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string ans;
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for (string s : strs) {
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int size = s.size();
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ans += string((const char*)& size, sizeof(size));
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ans += s;
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}
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return ans;
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}
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// Decodes a single string to a list of strings.
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vector<string> decode(string s) {
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vector<string> ans;
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int i = 0, n = s.size();
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int size = 0;
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while (i < n) {
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memcpy(&size, s.data() + i, sizeof(size));
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i += sizeof(size);
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ans.push_back(s.substr(i, size));
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i += size;
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}
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return ans;
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}
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};
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// Your Codec object will be instantiated and called as such:
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// Codec codec;
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// codec.decode(codec.encode(strs));

‎solution/0200-0299/0271.Encode and Decode Strings/Solution.go

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type Codec struct {
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}
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// Encodes a list of strings to a single string.
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func (codec *Codec) Encode(strs []string) string {
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ans := &bytes.Buffer{}
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for _, s := range strs {
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t := fmt.Sprintf("%04d", len(s))
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ans.WriteString(t)
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ans.WriteString(s)
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}
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return ans.String()
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}
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// Decodes a single string to a list of strings.
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func (codec *Codec) Decode(strs string) []string {
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ans := []string{}
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i, n := 0, len(strs)
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for i < n {
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t := strs[i : i+4]
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i += 4
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size, _ := strconv.Atoi(t)
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ans = append(ans, strs[i:i+size])
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i += size
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}
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return ans
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}
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// Your Codec object will be instantiated and called as such:
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// var codec Codec
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// codec.Decode(codec.Encode(strs));

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