solve: encode and decode strings

Author: sounmind

encode-and-decode-strings/sounmind.js

@@ -0,0 +1,56 @@
+from typing import List
+
+
+class Solution:
+    # Special character used as delimiter between length and actual string
+    delimiter = "$"
+
+    def encode(self, strs: List[str]) -> str:
+        """
+        Encodes a list of strings into a single string.
+        Format: [length]$[string][length]$[string]...
+        """
+        encoded = []
+        # Encode each word using the format: length + delimiter + word
+        for word in strs:
+            # Convert word length to string, add delimiter, then add the word itself
+            encoded.append(f"{len(word)}{self.delimiter}{word}")
+
+        # Join all encoded elements into a single string and return
+        return "".join(encoded)
+
+    def decode(self, encoded: str) -> List[str]:
+        """
+        Decodes a single string back to the original list of strings.
+        """
+        decoded = []  # List to store the decoded strings
+        current_index = 0  # Pointer to track current position in the encoded string
+
+        # Process the encoded string until we reach the end
+        while current_index < len(encoded):
+            # Starting from current_index, find the position of delimiter
+            delimiter_index = current_index
+
+            # Move forward until we find the delimiter character
+            while encoded[delimiter_index] != self.delimiter:
+                delimiter_index += 1
+
+            # Extract and convert the length prefix to integer
+            word_length = int(encoded[current_index:delimiter_index])
+
+            # Calculate the start position of the word (after the delimiter)
+            word_start = delimiter_index + 1
+
+            # Calculate the end position of the word
+            word_end = word_start + word_length
+
+            # Extract the word using the calculated positions
+            word = encoded[word_start:word_end]
+
+            # Add the decoded word to our result list
+            decoded.append(word)
+
+            # Move the current index to the end of this word for the next iteration
+            current_index = word_end
+
+        return decoded