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+#!/usr/bin/env lua
+
+--[[
+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
+--]]
+
+function get_points()
+    if #arg < 6 or math.fmod(#arg, 2) ~= 0 then
+        io.write("Usage: ch-1.lua x y x y x y ...\n")
+        os.exit(1)
+    end
+    local P = {}
+    for i=1, #arg, 2 do
+        local x = tonumber(arg[i])
+        local y = tonumber(arg[i+1])
+        table.insert(P, {x,y})
+    end 
+    return P
+end
+
+function in_line(pi, pj, pk)
+    -- compute cross product
+    dxc = pk[1] - pi[1];
+    dyc = pk[2] - pi[2];
+
+    dxl = pj[1] - pi[1];
+    dyl = pj[2] - pi[2];
+
+    cross = dxc * dyl - dyc * dxl;
+    
+    return cross == 0 and true or false
+end
+
+function max_in_line(P)
+    local max_count = 0
+    -- for each pair
+    for i=1, #P-1 do
+        for j=i+1, #P do
+            -- check other points against pair
+            local count = 0
+            for k=1, #P do
+                if in_line(P[i], P[j], P[k]) then
+                    count = count + 1
+                end
+            end
+            max_count = math.max(max_count, count)
+        end
+    end
+    
+    return max_count
+end
+
+io.write(max_in_line(get_points()), "\n")