LeetCode 535. Encode and Decode TinyURL

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版权声明：本文为博主原创文章，转载请注明出处：http://blog.jerkybible.com/2017/03/08/LeetCode-535-Encode-and-Decode-TinyURL/

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题目要求

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 the encode and decode methods for the TinyURL service. 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.

题意解析

完成短链接的编解码。

解法分析

没有用特别好的解法，就是一个字符串替换。

解题代码

	private static String TINT_URLBASE = "http://tinyurl.com/";
private static Map<String, String> URL_MAP = new HashMap<>();

/**
 * 创建指定数量的随机字符串
 * 
 * @param length
 * @return 随机字符串
 */
public String createRandomStreamUrl(int length) {
	String invitationCode = "";
	
	// 省略若干

	return invitationCode;
}

// Encodes a URL to a shortened URL.
public String encode(String longUrl) {
	String tinyUrlTail = createRandomStreamUrl(8);
	while (URL_MAP.keySet().contains(tinyUrlTail)) {
		tinyUrlTail = createRandomStreamUrl(8);
	}
	URL_MAP.put(tinyUrlTail, longUrl);
	return TINT_URLBASE + tinyUrlTail;
}

// Decodes a shortened URL to its original URL.
public String decode(String shortUrl) {
	int index = shortUrl.lastIndexOf("/");
	String tinyUrlTail = shortUrl.substring(index + 1);
	return URL_MAP.get(tinyUrlTail);
}