encode and decode strings solution

Author: JeonJe

encode-and-decode-strings/JeonJe.java

@@ -0,0 +1,34 @@
+import java.util.*;
+
+// TC: O(n)
+// SC: O(n)
+class Solution {
+
+    private static final String DELIMITER = ",";
+
+    // ["mydata"] -> "6,mydata"
+    public String encode(List<String> strs) {
+        StringBuilder sb = new StringBuilder();
+        for (String s : strs) {
+            sb.append(s.length()).append(DELIMITER).append(s);
+        }
+        return sb.toString();
+    }
+
+    // "6,mydata" -> ["mydata"]
+    public List<String> decode(String str) {
+        List<String> answer = new ArrayList<>();
+
+        int cursor = 0;
+        while (cursor < str.length()) {
+            int indexOfDelimiter = str.indexOf(DELIMITER, cursor);
+            int dataStart = indexOfDelimiter + 1;
+            int dataLength = Integer.parseInt(str.substring(cursor, indexOfDelimiter));
+
+            answer.add(str.substring(dataStart, dataStart + dataLength));
+            cursor = dataStart + dataLength;
+        }
+
+        return answer;
+    }
+}