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LeetCode 535. Encode and Decode TinyURL

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题目

原题在此

解析

基本是按照这个实现的.
一个随机字符串生成器加map储存.

代码

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#include <iostream>
#include <ctime>
#include <unistd.h>

class Solution {
public:

    // Encodes a URL to a shortened URL.
    string encode(string longUrl) {
        string str = gen_random(6);
        while(mp.find(str) != mp.end())
            str = gen_random(6);
        mp[str] = longUrl;
        return str;
    }

    // Decodes a shortened URL to its original URL.
    string decode(string shortUrl) {
        return mp[shortUrl];
    }

private:
    map<string, string> mp;
    
    string gen_random(const int len) {
        string tmp_s;
        static const char alphanum[] =
            "0123456789"
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            "abcdefghijklmnopqrstuvwxyz";

        srand( (unsigned) time(NULL) * getpid());
        tmp_s.reserve(len);
        for (int i = 0; i < len; ++i) 
            tmp_s += alphanum[rand() % (sizeof(alphanum) - 1)];

        return tmp_s;
    }
};

// Your Solution object will be instantiated and called as such:
// Solution solution;
// solution.decode(solution.encode(url));