How do I find duplicates in an array and display how many times they occurred?

user_2958656 0
Viewed 144798

I'm working on a code that prints out duplicated integers from an array with the number of their occurrence. I'm not allowed to use LINQ, just a simple code. I think I'm so close but confused about how to get a correct output: 

class Program
{
    static void Main(string[] args)
    {              
        int[] array = { 10, 5, 10, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12 };
        int count = 1;
        for (int i = 0; i < array.Length; i++)
        {
            for (int j = i; j < array.Length - 1 ; j++)
            {

               if(array[j] == array[j+1])
                  count = count + 1;
            }
            Console.WriteLine("\t\n " + array[i] + "occurse" + count);
            Console.ReadKey();
        }
    }
}
duplicates arrays c#
13 Answers
int[] arr = { 10, 5, 10, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12 };
var result = arr.GroupBy(x => x).Select(x => new { key = x.Key, val = x.Count() });       
foreach (var item in result)
{
    if(item.val > 1)
    {                
        Console.WriteLine("Duplicate value : {0}", item.key);
        Console.WriteLine("MaxCount : {0}", item.val);
    }

}

Console.ReadLine();
user_107854120 
public static void FindRepeating(int[] input) 
{
    for (var i = 0; i < input.Length; i++)
    {
        var abs = Math.Abs(input[i]);

        if (input[abs] >= 0)
            input[abs] = -input[abs];
        else
            Console.Write(abs + " ");
    }
}
user_93411250 
using System;
using System.Collections.Generic;

namespace ConsoleApp1
{
    /// <summary>
    /// How do you find the duplicate number on a given integer array?
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            int[] array = { 10, 5, 10, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12 };

            Dictionary<int, int> duplicates = FindDuplicate(array);

            Display(duplicates);

            Console.ReadLine();
        }

        private static Dictionary<T, int> FindDuplicate<T>(IEnumerable<T> source)
        {
            HashSet<T> set = new HashSet<T>();
            Dictionary<T, int> duplicates = new Dictionary<T, int>();

            foreach (var item in source)
            {
                if (!set.Add(item))
                {
                    if (duplicates.ContainsKey(item))
                    {
                        duplicates[item]++;
                    }
                    else
                    {
                        duplicates.Add(item, 2);
                    }
                }
            }

            return duplicates;
        }

        private static void Display(Dictionary<int, int> duplicates)
        {
            foreach (var item in duplicates)
            {
                Console.WriteLine($"{item.Key}:{item.Value}");
            }
        }
    }
}
user_34273240 
 class Program
{
    static void Main(string[] args)
    {
        int[] arr = { 2, 3, 2, 4, 5, 12, 2, 3, 3, 3, 12 };
        List<int> nums = new List<int>();
        List<int> count = new List<int>();
        nums.Add(arr[0]);
        count.Add(1);
        for (int i = 1; i < arr.Length; i++)
        {

            if(nums.Contains(arr[i]))
            {
                count[nums.IndexOf(arr[i])] += 1;
            }
            else
            {
                nums.Add(arr[i]);
                count.Add(1);
            }
        }

        for(int x =0; x<nums.Count;x++)
        {
            Console.WriteLine("number:"+nums[x] +"Count :"+ count[x]);
        }
        Console.Read();
    }
}
user_91162790
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