如何设计一个很小的URL或URL缩短器（） _URL缩短器

本文概述

C ++
Java
Python3

如何设计一个采用大网址的系统并将其转换为短6个字符的系统网址。假定URL已存储在数据库中, 并且每个URL都有一个关联的整数ID。
需要注意的重要一件事是, 长网址也应该可以从短网址中唯一地识别出来。所以我们需要一个
双射函数
一个简单的解决方案可能是哈希。使用哈希函数将长字符串转换为短字符串。在散列中, 可能是冲突(2个长URL映射到相同的短URL), 并且我们需要为每个长URL唯一的短URL, 以便我们可以返回长URL。
一种更好的解决方案是使用存储在数据库中的整数id并将该整数转换为最多6个字符长的字符串。这个问题基本上可以看作是一个基本转换问题, 其中我们有一个10位数字的输入数字, 我们想将其转换为6个字符长的字符串。
以下是有关URL中可能字符的一项重要观察。
URL字符可以是以下之一
1)小写字母[a]到[z], 共26个字符
2)大写字母[A至Z], 共26个字符
3)数字[‘ 0’ 到’ 9’ ], 共10个字符
一共有26 + 26 + 10 = 62个可能的字符。
因此, 任务是将十进制数转换为以62为基数的数字。
要获取原始的长URL, 我们需要在数据库中获取URL ID。可以使用以62为底的十进制转换获得id。
C ++

//C++ program to generate short url from integer id and //integer id back from short url. #include< iostream> #include< algorithm> #include< string> using namespace std; //Function to generate a short url from integer ID string idToShortURL( long int n) { //Map to store 62 possible characters char map[] = "abcdefghijklmnopqrstuvwxyzABCDEF" "GHIJKLMNOPQRSTUVWXYZ0123456789" ; string shorturl; //Convert given integer id to a base 62 number while (n) { //use above map to store actual character //in short url shorturl.push_back(map[n%62]); n = n/62; }//Reverse shortURL to complete base conversion reverse(shorturl.begin(), shorturl.end()); return shorturl; }//Function to get integer ID back from a short url long int shortURLtoID(string shortURL) { long int id = 0; //initialize result//A simple base conversion logic for ( int i=0; i < shortURL.length(); i++) { if ( 'a' < = shortURL[i] & & shortURL[i] < = 'z' ) id = id*62 + shortURL[i] - 'a' ; if ( 'A' < = shortURL[i] & & shortURL[i] < = 'Z' ) id = id*62 + shortURL[i] - 'A' + 26; if ( '0' < = shortURL[i] & & shortURL[i] < = '9' ) id = id*62 + shortURL[i] - '0' + 52; } return id; }//Driver program to test above function int main() { int n = 12345; string shorturl = idToShortURL(n); cout < < "Generated short url is " < < shorturl < < endl; cout < < "Id from url is " < < shortURLtoID(shorturl); return 0; }

Java

//Java program to generate short url from integer id and //integer id back from short url. import java.util.*; import java.lang.*; import java.io.*; class GFG { //Function to generate a short url from integer ID static String idToShortURL( int n) { //Map to store 62 possible characters char map[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" .toCharArray(); StringBuffer shorturl = new StringBuffer(); //Convert given integer id to a base 62 number while (n> 0 ) { //use above map to store actual character //in short url shorturl.append(map[n % 62 ]); n = n /62 ; } //Reverse shortURL to complete base conversion return shorturl.reverse().toString(); } //Function to get integer ID back from a short url static int shortURLtoID(String shortURL) { int id = 0 ; //initialize result //A simple base conversion logic for ( int i = 0 ; i < shortURL.length(); i++) { if ( 'a' < = shortURL.charAt(i) & & shortURL.charAt(i) < = 'z' ) id = id * 62 + shortURL.charAt(i) - 'a' ; if ( 'A' < = shortURL.charAt(i) & & shortURL.charAt(i) < = 'Z' ) id = id * 62 + shortURL.charAt(i) - 'A' + 26 ; if ( '0' < = shortURL.charAt(i) & & shortURL.charAt(i) < = '9' ) id = id * 62 + shortURL.charAt(i) - '0' + 52 ; } return id; } //Driver Code public static void main (String[] args) throws IOException { int n = 12345 ; String shorturl = idToShortURL(n); System.out.println( "Generated short url is " + shorturl); System.out.println( "Id from url is " + shortURLtoID(shorturl)); } }//This code is contributed by shubham96301

Python3

# Python3 code for above approach def idToShortURL( id ): map = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" shortURL = ""# for each digit find the base 62 while ( id> 0 ): shortURL + = map [ id % 62 ] id //= 62# reversing the shortURL return shortURL[ len (shortURL): : - 1 ]def shortURLToId(shortURL): id = 0 for i in shortURL: val_i = ord (i) if (val_i> = ord ( 'a' ) and val_i < = ord ( 'z' )): id = id * 62 + val_i - ord ( 'a' ) elif (val_i> = ord ( 'A' ) and val_i < = ord ( 'Z' )): id = id * 62 + val_i - ord ( 'Z' ) + 26 else : id = id * 62 + val_i - ord ( '0' ) + 52 return idif (__name__ = = "__main__" ): id = 12345 shortURL = idToShortURL( id ) print ( "Short URL from 12345 is : " , shortURL) print ( "ID from" , shortURL, "is : " , shortURLToId(shortURL))

输出如下：