如何设计一个系统来接收大的URL，比如“https://www.geeksforgeeks.org/count-sum-of-digits-in-numbers-from-1-to-n/“并将它们转换为一个6个字符的短URL。URL存储在数据库中，每个URL都有一个关联的整数id。 需要注意的一件重要事情是，长URL也应该与短URL唯一可识别。所以我们需要一个 双射函数
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我们强烈建议您在继续解决方案之前单击此处并进行练习。
一 简单解决方案 可能是散列。使用哈希函数将长字符串转换为短字符串。在散列中，这可能是冲突（两个长URL映射到同一个短URL），我们需要为每个长URL创建一个唯一的短URL，以便我们可以访问长URL。 A. 更好的解决方案 是使用存储在数据库中的整数id，并将整数转换为最多6个字符的字符串。这个问题基本上可以看作是一个基本的转换问题，我们有一个10位的输入数字，我们想把它转换成一个6个字符长的字符串。 下面是关于URL中可能的字符的一个重要观察结果。 URL字符可以是以下字符之一 1） 小写字母[‘A’到’z’]，总共26个字符 2） 大写字母表[‘A’到’Z’]，总共26个字符 3） 一个数字[‘0’到’9’，总共10个字符 总共有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。可以使用从62进制到十进制的转换来获得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 id if (__name__ = = "__main__" ): id = 12345 shortURL = idToShortURL( id ) print ( "Short URL from 12345 is : " , shortURL) print ( "ID from" , shortURL, "is : " , shortURLToId(shortURL)) |
C#
// C# program to generate short url from integer id and // integer id back from short url. using System; public 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(); String shorturl = "" ; // Convert given integer id to a base 62 number while (n > 0) { // use above map to store actual character // in short url shorturl+=(map[n % 62]); n = n / 62; } // Reverse shortURL to complete base conversion return reverse(shorturl); } static String reverse(String input) { char [] a = input.ToCharArray(); int l, r = a.Length - 1; for (l = 0; l < r; l++, r--) { char temp = a[l]; a[l] = a[r]; a[r] = temp; } return String.Join( "" ,a); } // 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[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 Code public static void Main(String[] args) { int n = 12345; String shorturl = idToShortURL(n); Console.WriteLine( "Generated short url is " + shorturl); Console.WriteLine( "Id from url is " + shortURLtoID(shorturl)); } } // This code is contributed by 29AjayKumar |
Javascript
<script> // Javascript program to generate short url from integer id and // integer id back from short url. // Function to generate a short url from integer ID function idToShortURL(n) { // Map to store 62 possible characters let map = "abcdefghijklmnopqrstuvwxyzABCDEF" "GHIJKLMNOPQRSTUVWXYZ0123456789" ; let shorturl = []; // Convert given integer id to a base 62 number while (n) { // use above map to store actual character // in short url shorturl.push(map[n % 62]); n = Math.floor(n / 62); } // Reverse shortURL to complete base conversion shorturl.reverse(); return shorturl.join( "" ); } // Function to get integer ID back from a short url function shortURLtoID(shortURL) { let id = 0; // initialize result // A simple base conversion logic for (let i = 0; i < shortURL.length; i++) { if ( 'a' <= shortURL[i] && shortURL[i] <= 'z' ) id = id * 62 + shortURL[i].charCodeAt(0) - 'a' .charCodeAt(0); if ( 'A' <= shortURL[i] && shortURL[i] <= 'Z' ) id = id * 62 + shortURL[i].charCodeAt(0) - 'A' .charCodeAt(0) + 26; if ( '0' <= shortURL[i] && shortURL[i] <= '9' ) id = id * 62 + shortURL[i].charCodeAt(0) - '0' .charCodeAt(0) + 52; } return id; } // Driver program to test above function let n = 12345; let shorturl = idToShortURL(n); document.write( "Generated short url is " + shorturl + "<br>" ); document.write( "Id from url is " + shortURLtoID(shorturl)); // This code is contributed by gfgking. </script> |
输出：
Generated short url is dnhId from url is 12345
优化：我们可以避免IDToSortUrl（）中的反向步骤。为了确保返回相同的ID，我们还需要将shortURLtoID（）更改为从头到尾处理字符。 本文的计算公式为 希瓦姆 。如果您发现任何不正确的地方，或者您想分享有关上述主题的更多信息，请发表评论。
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