Solution: Encode and Decode Strings

Author: obzva

encode-and-decode-strings/flynn.cpp

@@ -0,0 +1,58 @@
+/**
+ * Let's say sum of lengths of given strings N, and the length of the longest string M
+ * 
+ * Encode
+ * - Time complexity: O(N)
+ * - Space complexity: O(1)
+ * 
+ * Decode
+ * - Time complexity: O(N)
+ * - Space complexity: O(M)
+ */
+
+class Codec {
+public:
+
+    // Encodes a list of strings to a single string.
+    string encode(vector<string>& strs) {
+        string res = "";
+        for (auto str : strs) {
+            res += to_string(str.size());
+            res.push_back('.');
+            res += str;
+        }
+        return res;
+    }
+
+    // Decodes a single string to a list of strings.
+    vector<string> decode(string s) {
+        vector<string> res;
+        int str_size = 0;
+        string tmp = "";
+
+        auto it = s.begin();
+        while (it != s.end()) {
+            do {
+                str_size = str_size * 10 + (*it - '0');
+                it++;
+            } while (*it != '.');
+
+            it++;
+
+            for (int i = 0; i < str_size; i++) {
+                tmp.push_back(*it);
+                it++;
+            }
+
+            res.push_back(tmp);
+            str_size = 0;
+            tmp = "";
+        }
+
+        return res;
+    }
+};
+
+// Your Codec object will be instantiated and called as such:
+// Codec codec;
+// codec.decode(codec.encode(strs));