【LeetCode】535. TinyURL 的加密与解密

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#LeetCode #TinyURL 的加密与解密

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1. 题目描述：

TinyURL是一种URL简化服务， 比如：当你输入一个URL https://leetcode.com/problems/design-tinyurl 时，
它将返回一个简化的URL http://tinyurl.com/4e9iAk.

要求：设计一个 TinyURL 的加密 encode 和解密 decode 的方法。
你的加密和解密算法如何设计和运作是没有限制的，你只需要保证一个URL可以被加密成一个TinyURL，
并且这个TinyURL可以用解密方法恢复成原本的URL。

2. 解法：

public class Codec {
    private static HashMap<String,String> longUrlMap = new HashMap<String,String>();
	private static HashMap<String,String> shortUrlMap = new HashMap<String,String>();
    // Encodes a URL to a shortened URL.
    public String encode(String longUrl) {
        char[] code = new char[]{'1', '2', '3', '4', '5', '6', '7', '8', '9', '0','a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
                'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
        StringBuffer sb = new StringBuffer();
    	for(int i = 0; i < 6; i++){
    		int index = Math.abs(new Random().nextInt(62));
    		sb.append(String.valueOf(code[index]));
    	}
    	String shortUrl = "http://tinyurl.com/"+sb.toString();
    	longUrlMap.put(shortUrl, longUrl);
    	shortUrlMap.put(longUrl, shortUrl);
    	return shortUrl;
    }

    // Decodes a shortened URL to its original URL.
    public String decode(String shortUrl) {
        return longUrlMap.get(shortUrl);
    }
}

// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.decode(codec.encode(url));

3.eclipse 可调试：

package single100;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Random;

public class Codec535 {

	private static HashMap<String,String> longUrlMap = new HashMap<String,String>();
	private static HashMap<String,String> shortUrlMap = new HashMap<String,String>();
	public static void main(String[] args) {
		
		String longUrl = "https://leetcode.com/problems/design-tinyurl";
		
		System.out.println(encode(longUrl));

	}

	// Encodes a URL to a shortened URL.
    public static String encode(String longUrl) {
        char[] code = new char[]{'1', '2', '3', '4', '5', '6', '7', '8', '9', '0','a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
                'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
        StringBuffer sb = new StringBuffer();
    	for(int i = 0; i < 6; i++){
    		int index = Math.abs(new Random().nextInt(62));
    		sb.append(String.valueOf(code[index]));
    	}
    	String shortUrl = "http://tinyurl.com/"+sb.toString();
    	longUrlMap.put(shortUrl, longUrl);
    	shortUrlMap.put(longUrl, shortUrl);
    	return shortUrl;
    }

    // Decodes a shortened URL to its original URL.
    public static String decode(String shortUrl) {
        
    	return longUrlMap.get(shortUrl);
    }
}

4.性能：