How to find out whether the list contains missing elements or not

I am having a requirement like to find out the missing numbers in the list available. I implemented a code but i am unable to get for some of the sequences.

Suppose if i have my list elements as 1,3 i would like to return this as false as 2 is missing.

If i have 1,2,3 i would like to return true as it is in sequence.

Like that i have random numbers in my list so can any one give me the logic for this

I tried this but for some conditions it is not working

int iMax = 0;
        int iMin = 0;

        iMin = (int)lstSequence[0];

        for (int iLoop = 0; iLoop < lstSequence.Count; iLoop++)
        {
            iMax = (int)lstSequence[iLoop];
        }

        for (int icompare = iMin; icompare <= iMax; icompare++)
        {
            if (icompare == iMin || icompare == iMax)
            {
            }
            else
            {
                if (lstSequence.Contains(icompare))
                {
                    seq_flag = true;
                }
                else
                {
                    seq_flag = false;
                }
            }
        }

This is how I'd do it. I'm assuming you're only interested in ascending sequences:

using System;

using System.Collections.Generic;

class Program

{

static void Main()

{

List lstSequence = new List{1, 3};

bool isSequential = IsSequential(lstSequence);

Console.WriteLine(isSequential); // false

lstSequence.Insert(1, 2);

isSequential = IsSequential(lstSequence);

Console.WriteLine(isSequential); // true

Console.ReadKey();

}

static bool IsSequential(List lstSequence)

{

if (lstSequence == null || lstSequence.Count == 0) return false;

if (lstSequence.Count == 1) return true;

bool result = true;

for(int i = 1; i < lstSequence.Count; i++)

{

if (lstSequence[i] != lstSequence[i - 1] + 1)

{

result = false;

break;

}

return result;

}

2 Replies

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Vulpes15y ago
Accepted answer
This is how I'd do it. I'm assuming you're only interested in ascending sequences:

using System;
using System.Collections.Generic;

class Program
{
static void Main()
{
List lstSequence = new List{1, 3};
bool isSequential = IsSequential(lstSequence);
Console.WriteLine(isSequential); // false
lstSequence.Insert(1, 2);
isSequential = IsSequential(lstSequence);
Console.WriteLine(isSequential); // true
Console.ReadKey();
}

static bool IsSequential(List lstSequence)
{
if (lstSequence == null || lstSequence.Count == 0) return false;
if (lstSequence.Count == 1) return true;
bool result = true;

for(int i = 1; i < lstSequence.Count; i++)
{
if (lstSequence[i] != lstSequence[i - 1] + 1)
{
result = false;
break;
}
}

return result;
}
}
Chaitanya15y ago
Thanks Vulpes