multiple arraylist repeat subjectname display in sequence

Question

Answer in c# also help me.

I tried this code for if i have duplicate string in multiple arraylist it update and display in sequence as before.

maths
english
maths
hindi
english
science
Economics
scince

i need output like this

maths_1
english_1
maths_2
hindi
science_1
Economics
scince_2

i tried this code but output is not in sequence**

Dim subjectCounts As Dictionary(Of String, Integer) = New Dictionary(Of String, Integer)
            For Each subject As String In arraysub
                If subjectCounts.ContainsKey(subject) Then
                    subjectCounts(subject) = (subjectCounts(subject) + 1)
                Else
                    subjectCounts.Add(subject, 1)
                End If
            Next
            Dim output As List(Of String) = New List(Of String)

            For Each pair As KeyValuePair(Of String, Integer) In subjectCounts
                If (pair.Value > 1) Then
                    Dim i As Integer = 1
                    Do While (i <= pair.Value)
                        output.Add((i.ToString + ("_" + pair.Key)))

                        i = (i + 1)
                    Loop
                Else
                    output.Add(pair.Key)
                End If
            Next

Answer 1

I think this generates the output you want

First let us check if the subject need to have the "_#" ending

now we run throught the subject, and add the _# ending for everyone that has more then one occurence. The order will be the same as the input, since we run through it. The counting will generated on the fly, so this will be correct.

    Dim hasMultiple As New Dictionary(Of String, Boolean)
    For Each subject As String In arraysub
        If hasMultiple.ContainsKey(subject) Then
            hasMultiple(subject) =  True
        Else
            hasMultiple.Add(subject, False)
        End If
    Next

    Dim output As New List(Of String)
    Dim subCount As New Dictionary(Of String, Integer) 
    For Each subject As String In arraysub
        If Not subCount.ContainsKey(subject) Then
            subCount.Add(subject, 0)
        End If
        subCount(subject) += 1
        If hasMultiple(subject) Then
            output.Add(subject & "_" & subCount(subject))
        Else
            output.Add(subject)
        End If
    Next