feat: Encode and Decode Strings #238

Author: donghyeon95

encode-and-decode-strings/donghyeon95.java

@@ -0,0 +1,57 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class Solution {
+	/*
+	 * @param strs: a list of strings
+	 * @return: encodes a list of strings to a single string.
+	 */
+	String cDel = "&";
+	String sDel = ";";
+
+	// Encodes a list of strings to a single string
+	public String encode(List<String> strs) {
+		if (strs.isEmpty()) return null;
+
+		StringBuilder result = new StringBuilder();
+		for (int i =0; i<strs.size(); i++) {
+			String str = strs.get(i);
+			StringBuilder temp = new StringBuilder();
+			for (char c : str.toCharArray()) {
+				temp.append((int) c).append(cDel);
+			}
+
+			result.append(temp);
+			if (i != strs.size()-1)  result.append(sDel);
+		}
+		return result.toString();
+	}
+
+	// Decodes a single string to a list of strings
+	public List<String> decode(String str) {
+		if (str==null)
+			return new ArrayList<>();
+
+		List<String> result = new ArrayList<>();
+		String[] strs = str.split(sDel, -1);
+		for (String s : strs) {
+			if (s.isEmpty()) {
+				result.add("");
+				continue;
+			}
+			String[] chars = s.split(cDel);
+			String decoded = Arrays.stream(chars)
+				.filter(sr -> !sr.isEmpty())
+				.mapToInt(Integer::parseInt)
+				.mapToObj(ascii -> (char) ascii)
+				.map(String::valueOf)
+				.collect(Collectors.joining());
+			result.add(decoded);
+		}
+		return result;
+	}
+}
+
+