2022-04-23 Daily-Challenge

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In: DailyChallenge

Today I have done leetcode's April LeetCoding Challenge with cpp.

April LeetCoding Challenge 23

Description

Encode and Decode TinyURL

Note: This is a companion problem to the System Design problem: Design TinyURL.

TinyURL is a URL shortening service where you enter a URL such as https://leetcode.com/problems/design-tinyurl and it returns a short URL such as http://tinyurl.com/4e9iAk. Design a class to encode a URL and decode a tiny URL.

There is no restriction on how your encode/decode algorithm should work. You just need to ensure that a URL can be encoded to a tiny URL and the tiny URL can be decoded to the original URL.

Implement the Solution class:

  • Solution() Initializes the object of the system.
  • String encode(String longUrl) Returns a tiny URL for the given longUrl.
  • String decode(String shortUrl) Returns the original long URL for the given shortUrl. It is guaranteed that the given shortUrl was encoded by the same object.

Example 1:

Input: url = "https://leetcode.com/problems/design-tinyurl"
Output: "https://leetcode.com/problems/design-tinyurl"

Explanation:
Solution obj = new Solution();
string tiny = obj.encode(url); // returns the encoded tiny url.
string ans = obj.decode(tiny); // returns the original url after deconding it.

Constraints:

  • 1 <= url.length <= 104
  • url is guranteed to be a valid URL.

Solution

class Solution {
public:
  unordered_map<string, string> mp;
  unordered_map<string, string> rmp;
  int count = 0;
  // Encodes a URL to a shortened URL.
  string encode(string longUrl) {
    if(!mp.count(longUrl)) {
      string cnt = to_string(count++);
      mp[longUrl] = cnt;
      rmp[cnt] = longUrl;
    }
    return mp[longUrl];
  }

  // Decodes a shortened URL to its original URL.
  string decode(string shortUrl) {
    return rmp[shortUrl];
  }
};

// Accepted
// 739/739 cases passed (6 ms)
// Your runtime beats 44.57 % of cpp submissions
// Your memory usage beats 16.54 % of cpp submissions (7.4 MB)
Algorithm