using System;

using System.Linq;

using System.Collections.Generic;

using Newtonsoft.Json;

​

public class Program

{

    public static void Main()

    {

    string jsonOutput = "[{\"Title\":\"Our Company Homepage\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Company\",\"RootGroup\":\"Company\",\"SortOrder\":1},{\"Title\":\"Business Units\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Company\",\"RootGroup\":\"Company\",\"SortOrder\":1},{\"Title\":\"2019 Flight Plan\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Company\",\"RootGroup\":\"Company\",\"SortOrder\":1},{\"Title\":\"Our Future Is Global\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Company\",\"RootGroup\":\"Company\",\"SortOrder\":1},{\"Title\":\"No One Better Connects the World\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Company\",\"RootGroup\":\"Company\",\"SortOrder\":1},{\"Title\":\"Employess Directory\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Directories\",\"RootGroup\":\"Company\",\"SortOrder\":2},{\"Title\":\"ATL Campus\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Directories\",\"RootGroup\":\"Company\",\"SortOrder\":2},{\"Title\":\"MSP Campus\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Directories\",\"RootGroup\":\"Company\",\"SortOrder\":2},{\"Title\":\"Mailing and Shipping Addresses\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Directories\",\"RootGroup\":\"Company\",\"SortOrder\":2},{\"Title\":\"Rules of the Road\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Culture\",\"RootGroup\":\"Company\",\"SortOrder\":3},{\"Title\":\"The Way We Fly\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Culture\",\"RootGroup\":\"Company\",\"SortOrder\":3},{\"Title\":\"Delta Board Council\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Culture\",\"RootGroup\":\"Company\",\"SortOrder\":3},{\"Title\":\"Global Diversity and Inclusion\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Culture\",\"RootGroup\":\"Company\",\"SortOrder\":3},{\"Title\":\"Business Resource Groups\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Community\",\"RootGroup\":\"Company\",\"SortOrder\":4},{\"Title\":\"Community Engagement\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Community\",\"RootGroup\":\"Company\",\"SortOrder\":4},{\"Title\":\"Responsibility\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Community\",\"RootGroup\":\"Company\",\"SortOrder\":4},{\"Title\":\"Delta Clubs\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Community\",\"RootGroup\":\"Division\",\"SortOrder\":4},{\"Title\":\"Delta People Care\",\"RedirectionUrl\":\"#\",\"ParentGroup\":\"Community\",\"RootGroup\":\"Division\",\"SortOrder\":4}]";

            var obj = JsonConvert.DeserializeObject<List<Items>>(jsonOutput);

        var formatJson = obj.GroupBy(t => t.ParentGroup).ToDictionary(wrap => wrap.Key);

            var json = JsonConvert.SerializeObject(formatJson, Formatting.Indented);

        Console.WriteLine(json);

    }

    public class Items

    {

        public string Title { get; set; }

        public string RedirectionUrl { get; set; }

        public string ParentGroup { get; set; }

        public string RootGroup { get; set; }

        public int SortOrder { get; set; }

    }

}