encode-and-encode-strings

Author: taewanseoul

encode-and-decode-strings/taewanseoul.ts

@@ -0,0 +1,38 @@
+/**
+ * 659 · Encode and Decode Strings
+ * Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings.
+ * Please implement encode and decode
+ *
+ * https://leetcode.com/problems/encode-and-decode-strings/description/
+ * https://www.lintcode.com/problem/659/
+ *
+ */
+
+// O(n) time
+// O(1) space
+function encode(strs: string[]): string {
+  let result = "";
+
+  for (const str of strs) {
+    result += `${str.length}#${str}`;
+  }
+
+  return result;
+}
+
+// O(n) time
+// O(n) space
+function decode(str: string) {
+  const result: string[] = [];
+
+  let i = 0;
+  while (i < str.length) {
+    let pos = str.indexOf("#", i);
+    const len = Number(str.slice(i, pos));
+    const word = str.slice(pos + 1, pos + 1 + len);
+    result.push(word);
+    i = pos + 1 + len;
+  }
+
+  return result;
+}