LeetCode in Kotlin

535. Encode and Decode TinyURL

Medium

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 Codec {
    private val map: MutableMap<String, String> = HashMap()
    private var n = 0

    // Encodes a URL to a shortened URL.
    fun encode(longUrl: String): String {
        n++
        var ans = "http://tinyurl.com/"
        ans += n.toString()
        map[ans] = longUrl
        return ans
    }

    // Decodes a shortened URL to its original URL.
    fun decode(shortUrl: String): String? {
        return map[shortUrl]
    }
}

/*
 * Your Codec object will be instantiated and called as such:
 * var obj = Codec()
 * var url = obj.encode(longUrl)
 * var ans = obj.decode(url)
 */

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