Why is my quicksort not working properly? - arrays

Question

I am working on sorting an array of objects in multiple ways. The objects are for areas, and I will be sorting data for those areas (more specifically population, concentration of water contaminants, and whether the area violates legal or health based water limits. My sorting results are almost accurate, and they are only off 5 spots out of 100.
t is a one character string that contains a keycode for how to sort the areas. For example, if t <-- "p", then it would test for population between two areas and return true or false.
Beforehand,
statusL <-- True statusH <-- True high <-- length
Code:
Function partition(a() As Area, High As Long, Low As Long, t As String, progress As Boolean)
Dim pivot As Area
Dim i As Long, j As Long
Set pivot = a(High)
i = Low - 1
j = Low
For j = Low To High - 1
If testAreas(a(j), pivot, t) Then
i = i + 1
Call swap(a(), i, j)
End If
Next j
Call swap(a(), i + 1, High)
If progress Then
partition = i - 1
Else
partition = i + 1
End If
End Function
Function QuickSort(a() As Area, High As Long, Low As Long, t As String, statusH As Boolean, statusL As Boolean, rounds As Long, oldPivot As Long, progress As Boolean)
Dim pivot As Long
If Low < High Then
pivot = partition(a(), High, Low, t, progress)
If rounds = 0 Then
oldPivot = pivot
End If
rounds = rounds + 1
If statusH = True Then
If pivot >= High - 1 Then
statusH = False
End If
Call QuickSort(a(), High, pivot - 1, t, statusH, statusL, rounds, oldPivot, progress)
End If
''''''''''''''''
If progress = False Then
pivot = oldPivot
End If
progress = True
''''''''''''''''
If statusL = True Then
If pivot <= 1 Then
statusL = False
End If
Call QuickSort(a(), pivot + 1, 0, t, statusH, statusL, rounds, oldPivot, progress)
End If
End If
End Function
Function swap(a() As Area, index1 As Long, index2 As Long)
Dim x As Area
Set x = a(index1)
Set a(index1) = a(index2)
Set a(index2) = x
End Function
Function testAreas(a As Area, b As Area, t As String)
testAreas = False
If t = "m" Then
If a.max <= b.max Then
testAreas = True
End If
End If
If t = "p" Then
Dim p1 As Double, p2 As Double
p1 = a.pop
p2 = b.pop
If p1 <= p2 Then
testAreas = True
End If
End If
If t = "l" Then
Dim L1 As Long, L2 As Long
L1 = a.ll
L2 = b.ll
If L1 <= L2 Then
testAreas = True
End If
End If
If t = "h" Then
Dim h1 As Long, h2 As Long
h1 = a.hbl
h2 = b.hbl
If h1 <= h2 Then
testAreas = True
End If
End If
If t = "s" Then
If a.state <= b.state Then
testAreas = True
End If
End If
End Function
The order I am getting looks like this:
221351,30948,20602,12300,11702,8980,2342,2300,1395,1475,1005,993,852,775,935, 904,975,654,650,600,794,650,740,493,795
...and as this goes down, it gets increasingly inaccurate then close to the end it becomes more accurate.

Answer 1

I don't understand the need for the progress parameter. For quicksort, if the pivot swap is using i+1, then the partition function should be returning i+1. To avoid stack overflow, use recursion on the smaller part, then loop back for the larger part. Example C++ code using Lomuto partition scheme:
void QuickSort(uint64_t a[], int lo, int hi)
{
while (lo < hi){
uint64_t p = a[hi];
int i = lo;
for (int j = lo; j < hi; ++j){
if (a[j] < p){
std::swap(a[j], a[i]);
++i;
}
}
std::swap(a[i], a[hi]);
if(i - lo <= hi - i){
QuickSort(a, lo, i-1);
lo = i+1;
} else {
QuickSort(a, i+1, hi);
hi = i-1;
}
}
}