add Encode and Decode Strings solution

Author: HoonDongKang

encode-and-decode-strings/HoonDongKang.ts

@@ -0,0 +1,37 @@
+/**
+ * [Problem]: [659] Encode and Decode Strings
+ *
+ * (https://www.lintcode.com/problem/659/)
+ */
+
+//시간복잡도 O(n)
+//공간복잡도 O(1)
+
+function encode(strs: string[]): string {
+    return strs.join("😄");
+}
+function decode(s: string): string[] {
+    return s.split("😄");
+}
+
+// 시간복잡도: O(n)
+// 공간복잡도: O(n)
+function encode(strs: string[]): string {
+    return strs.map((str) => `${str.length}:${str}`).join("");
+}
+
+// 시간복잡도: O(n)
+// 공간복잡도: O(n)
+function decode(str: string): string[] {
+    const result: string[] = [];
+    let index = 0;
+    while (index < str.length) {
+        const separatorIndex = str.indexOf(":", index);
+        const length = +str.slice(index, separatorIndex);
+        const endIndex = separatorIndex + 1 + length;
+
+        result.push(str.slice(separatorIndex + 1, endIndex));
+        index = endIndex;
+    }
+    return result;
+}