Solution JsonConverter

JsonConverter.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;

namespace JsonConverter
{
    /*
     * Nowadays it's important to know how to work with JSON, in this exercise candidate must convert a HTTP query string into JSON
        #######################################################
        Input: name=john&name=smith&age=30&city=chicago&married=true
        #######################################################
        Output: {"name":["john","smith"],"age": 30,"city":"chicago","married":true}
     */

    class Program
    {
        static void Main(string[] args)
        {
            var result = Solution("name=john&name=smith&age=30&city=chicago&married=true");
            Console.WriteLine(result);
            Console.ReadKey();
        }

        private static string Solution(string query)
        {
            var dictionary = new Dictionary<string, List<Token>>();

            string[] querySplit = query.Split('&');

            foreach(string split in querySplit)
            {
                string[] keyValue = split.Split('=');
                string key = keyValue[0];
                string value = keyValue[1];

                if(dictionary.ContainsKey(key))
                {
                    dictionary[key].Add(new Token(value));
                } else
                {
                    dictionary.Add(key, new List<Token> { new Token(value) });
                }
            }

            StringBuilder sb = new StringBuilder();
            sb.Append('{');
            for(int i = 0; i < dictionary.Count; i++)
            {
                var keyValue = dictionary.ElementAt(i);
                sb.Append('\"' + keyValue.Key + '\"' + ":");

                int size = keyValue.Value.Count;
                if(size > 1) // if element is array
                {
                    sb.Append("[");
                    for(int j = 0; j < size; j++)
                    {
                        var token = keyValue.Value[j];
                        sb.Append(token);

                        bool isNotLastToken = j + 1 != size;
                        if (isNotLastToken)
                        {
                            sb.Append(",");
                        }
                    }
                    sb.Append("]");
                } else // if element is a field
                {
                    sb.Append(keyValue.Value.First());
                }

                bool isNotLastKeyValue = i + 1 != dictionary.Count;
                if (isNotLastKeyValue)
                {
                    sb.Append(",");
                }
            }
            sb.Append('}');

            return sb.ToString();
        }
    }

    class Token
    {
        private string _value;

        public Token(string value)
        {
            _value = value;
        }

        public override string ToString()
        {
            if(bool.TryParse(_value, out _))
            {
                return _value;
            } else if(int.TryParse(_value, out _))
            {
                return _value;
            } else
            {
                return '\"' + _value + '\"';
            }
        }
    }
}