naive algorithm

store-credit.vb

Imports System.IO

Module Module1

    Sub Main()
        Dim startTime As DateTime = Now

        Dim N As Integer 'number of test cases
        Dim C As Integer 'amount of credit
        Dim l As Integer 'number of items in store
        Dim P As List(Of Integer) 'cost of item
        Dim answer() As Integer

        'parse the file
        Dim inputName As String = "c:\users\joel\documents\visual studio 2010\Projects\cj-storecredit\A-small.in"
        Dim inputStream As StreamReader = New StreamReader(inputName)
        Dim outputName As String = "c:\users\joel\documents\visual studio 2010\Projects\cj-storecredit\A-small.out"
        Dim outputStream As StreamWriter = New StreamWriter(outputName, False)

        N = CInt(inputStream.ReadLine)

        For caseNumber As Integer = 1 To N
            C = CInt(inputStream.ReadLine)
            l = CInt(inputStream.ReadLine)
            P = inputStream.ReadLine.Split(" ").ToList().ConvertAll(Function(i) CInt(i))

            answer = SolveLine(C, P)

            outputStream.WriteLine(String.Format("Case #{0}: {1} {2}", caseNumber, answer(0), answer(1)))
        Next

        outputStream.Close()

        Dim runLength As Global.System.TimeSpan = Now.Subtract(startTime)
        Dim millisecs As Integer = runLength.TotalMilliseconds
        Console.WriteLine(millisecs)
        Console.ReadLine()
    End Sub

    Public Function SolveLine(ByVal C As Integer, ByVal P As List(Of Integer)) As Integer()
        Dim lowItem, highItem As Integer

        For outer As Integer = 0 To P.Count - 1
            For inner As Integer = outer + 1 To P.Count - 1
                If P(outer) + P(inner) = C Then
                    lowItem = outer + 1
                    highItem = inner + 1
                    Exit For
                End If
            Next
            If lowItem <> Nothing Then Exit For
        Next

        Return New Integer() {lowItem, highItem}
    End Function
End Module