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' Challenge 093
'
' TASK #1 › Max Points
' Submitted by: Mohammad S Anwar
' You are given set of co-ordinates @N.
'
' Write a script to count maximum points on a straight line when given co-ordinates plotted on 2-d plane.
'
' Example 1:
' |
' | x
' | x
' | x
' + _ _ _ _
'
' Input: (1,1), (2,2), (3,3)
' Output: 3
' Example 2:
' |
' |
' | x x
' | x
' | x x
' + _ _ _ _ _
'
' Input: (1,1), (2,2), (3,1), (1,3), (5,3)
' Output: 3
Type PointType
x as Integer
y as Integer
End Type
Dim Shared points() as PointType
' read points from command line
Sub read_points()
Dim i as Integer
i = 0
Do While Command(1+2*i) <> ""
Redim Preserve points(i) as PointType
points(i).x = Val(Command(1+2*i))
points(i).y = Val(Command(1+2*i+1))
i = i+1
Loop
End Sub
' check if three points are in a line
Function three_in_line(i as PointType, j as PointType, k as PointType) as Boolean
Dim dxc as Integer, dyc as Integer, dxl as Integer, dyl as Integer, cross as Integer
dxc = k.x - i.x: dyc = k.y - i.y
dxl = j.x - i.x: dyl = j.y - i.y
cross = dxc * dyl - dyc * dxl
three_in_line = (cross = 0)
End Function
' count total points through given two points
Function count_in_line(i as PointType, j as PointType) as Integer
Dim npoints as Integer
Dim k as Integer
npoints = 0
For k=LBound(points) to UBound(points)
If three_in_line(i, j, points(k)) Then
npoints = npoints+1
End If
Next k
count_in_line = npoints
End Function
' count max points in line
Function count_max_in_line() as Integer
Dim max_npoints as Integer, npoints as Integer
Dim i as Integer, j as Integer
max_npoints = 0
For i=LBound(points) to UBound(points)-1
For j=i+1 to UBound(points)
npoints = count_in_line(points(i), points(j))
If npoints > max_npoints Then
max_npoints = npoints
End If
Next j
Next i
count_max_in_line = max_npoints
End Function
' main
read_points
print count_max_in_line()
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