#Exchange the two value.
function ExchangeValue($i,$j, $studentScore, $studentName)
{
    #Exchange the score.
    $s = $studentScore[$i] 
    $studentScore[$i] = $studentScore[$j]
    $studentScore[$j] = $s
    #Exchange the name.
    $n = $studentName[$i] 
    $studentName[$i] = $studentName[$j]
    $studentName[$j] = $n
}
function SortScores($left, $right, $studentScore, $studentName)
{
    if($left -le $right)
    {
        #Sort begin.
        #The $left is base number, the $left and $right also represents the location of the sentries' start points.  
        $i = $left
        $j = $right
        #The right sentry must go first every time while the sentries not meet each other.
        while($i -ne $j)
        {
            while(($studentScore[$j] -ge $studentScore[$left]) -and ($j -gt $i))
            {
                $j--
            }
            #And then the left one.
            while(($studentScore[$i] -le $studentScore[$left]) -and ($i -lt $j))
            {
                $i++
            }
            #If the left entry doesn't meet the right entry, exchange the left and right number.
            If($i -lt $j)
            {
                ExchangeValue $i $j $studentScore $studentName
            }
        }
        #Exchange the value from the locations of the left entry and the base number.
        ExchangeValue $left $i $studentScore $studentName
        #Now "$i" is the new location of the base number.
        #Sort the new left part.
        $newRight = $i-1
        $newLeft = $i+1
        SortScores $left $newRight $studentScore $studentName
        SortScores $newLeft $right $studentScore $studentName
    }
}
function PrintSortedScores($count, $studentScore, $studentName){
    #Print the sorted result.
    Write-Host "Below is the sorted result:"
    for($i=0;$i -le $count-1;$i++)
    {
        $j=$i+1
        $tip = "NO."+$j+":"+$studentName[$i]+",score:"+$studentScore[$i]
        Write-Host $tip -ForegroundColor Green
    }
}
#This is the entry of this program.
#Collect the students' scores.
$count = Read-Host "Enter the amout number of the students"
#Convert to int type.
$count = [int]$count
$studentName = New-Object System.Collections.ArrayList
$studentScore = New-Object System.Collections.ArrayList
for($i=1;$i -le $count;$i++)
{
    $name = Read-Host "Enter the name"
    $score= Read-Host "Enter the score"
    #Convert to int type.
    $score = [float]$score
    $studentName.Add($name)
    $studentScore.Add($score)
}
$leftNum = 0
$rightNum = $count - 1
SortScores $leftNum $rightNum $studentScore $studentName
PrintSortedScores $count $studentScore $studentName