Merge branch 'master' of github.com:seaker/perlweeklychallenge-club

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diff --git a/challenge-101/paulo-custodio/lua/ch-2.lua b/challenge-101/paulo-custodio/lua/ch-2.lua
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+#!/usr/bin/env lua
+
+--[[
+Challenge 101
+
+TASK #2 › Origin-containing Triangle
+Submitted by: Stuart Little
+You are given three points in the plane, as a list of six co-ordinates: 
+A=(x1,y1), B=(x2,y2) and C=(x3,y3).
+
+Write a script to find out if the triangle formed by the given three 
+co-ordinates contain origin (0,0).
+
+Print 1 if found otherwise 0.
+--]]
+
+function sign(x1,y1,x2,y2,x3,y3)
+    return (x1 - x3) * (y2 - y3) - (x2 - x3) * (y1 - y3)
+end
+
+function point_in_triangle(xp,yp, x1,y1,x2,y2,x3,y3)
+    local d1 = sign(xp,yp, x1,y1, x2,y2)
+    local d2 = sign(xp,yp, x2,y2, x3,y3)
+    local d3 = sign(xp,yp, x3,y3, x1,y1)
+
+    local has_neg
+    if (d1 < 0) or (d2 < 0) or (d3 < 0) then 
+        has_neg = true
+    else
+        has_neg = false
+    end
+    
+    local has_neg = (d1 < 0) or (d2 < 0) or (d3 < 0)
+    local has_pos = (d1 > 0) or (d2 > 0) or (d3 > 0)
+
+    if has_neg and has_pos then
+        return 0
+    else
+        return 1
+    end
+end
+
+io.write(point_in_triangle(0,0, 
+                           tonumber(arg[1]), tonumber(arg[2]),
+                           tonumber(arg[3]), tonumber(arg[4]),
+                           tonumber(arg[5]), tonumber(arg[6])), "\n")