Solution Review: Trace the Complete Path of a Journey

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace chapter_9
{
    class challenge_4
    {
        static string tracePath(Dictionary<string, string> map)
        {
            string result = "";
            //Create a reverse Map of given map i.e if given map has (N,C) then reverse map will have (C,N) as key value pair
            //Traverse original map and see if corresponding key exist in reverse Map
            //If it doesn't exist then we found our starting point.
            //After starting point is found, simply trace the complete path from original map.
            Dictionary<string, string> reverseMap = new Dictionary<string, string>();
            
            //To fill reverse map, iterate through the given map
            foreach (string key in map.Keys)
            {
                // map is an instance of Dictionary<string, string>
                // type key stores the key part  and
                // map[key] stores the value part
                reverseMap[map[key]] = key;
            }
            //Find the starting point of the journey
            string from = "";
            foreach (string key in map.Keys)
            {
                if (!reverseMap.ContainsKey(key) )
                {
                    from = key;
                    break;
                }
            }
            //Trace complete path
            string to = map[from];
          
            while ((map.ContainsKey(to)))
            {
                result += from + "->" + to + " ";
                from = to;
                to = map[to];
            }
            result += from + "->" + to + " ";
            return result;
        }
        static void Main(string[] args)
        {
            Dictionary<string, string> hMap = new Dictionary<string, string>();
            hMap["NewYork"] = "Chicago";
            hMap["Boston"] = "Texas";
            hMap["Missouri"] = "NewYork";
            hMap["Texas"] = "Missouri";
            Console.WriteLine(tracePath(hMap));
            
        }
    }
}