using System;

using System.Collections.Generic;

using System.IO;

using OfficeOpenXml;

​

namespace ExcelDuplicateRemover

{

    public class Program

    {

        public static void Main(string[] args)

        {

            var inputExcelFile = "input.xlsx";

            var outputExcelFile = "output.xlsx";

            int startRow = 1;

            int[] columnIndices = {0, 1, 2};

            using (var package = new ExcelPackage(new FileInfo(inputExcelFile)))

            {

                var worksheet = package.Workbook.Worksheets["Sheet1"];

                if (worksheet == null)

                {

                    Console.WriteLine("Worksheet not found. Make sure the worksheet name is correct.");

                    return;

                }

​

                var duplicates = new HashSet<int>();

                foreach (int columnIndex in columnIndices)

                {

                    var seenNames = new HashSet<string>();

                    for (int rowIndex = startRow; rowIndex <= worksheet.Dimension.End.Row; rowIndex++)

                    {

                        var cell = worksheet.Cells[rowIndex, columnIndex + 1];

                        var cellValue = cell.Text;

                        if (seenNames.Contains(cellValue))

                        {

                            duplicates.Add(rowIndex);

                        }

                        else

                        {

                            seenNames.Add(cellValue);

                        }

                    }

                }

​

                Console.WriteLine("Deleting rows");

                var sortedDuplicates = new List<int>(duplicates);

                sortedDuplicates.Sort((a, b) => -1 * a.CompareTo(b));

                foreach (int rowIndex in sortedDuplicates)

                {

                    worksheet.DeleteRow(rowIndex);

                }

​

                package.SaveAs(new FileInfo(outputExcelFile));

            }

​

            Console.WriteLine("Done. Duplicates removed and saved to {outputExcelFile}");

        }

    }

}