From 5efce534e98f3b3c9bb4d22d079d5c262e2749dc Mon Sep 17 00:00:00 2001
From: JBlackNut <jnuthong@gmail.com>
Date: Mon, 2 Dec 2013 22:27:11 -0800
Subject: [PATCH 1/2] Initial commit

---
 README.md | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 README.md

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..bf7db3f
--- /dev/null
+++ b/README.md
@@ -0,0 +1,4 @@
+Python-Algorithm-Code-
+======================
+
+Python code for some algorithm practice

From f325418b317c94d9d7404273ba49aba6582c4bef Mon Sep 17 00:00:00 2001
From: Jianbin <jnuthong@gmail.com>
Date: Tue, 13 Oct 2015 23:12:39 +0800
Subject: [PATCH 2/2] line_segment_intersection.py

Given two street, each street is consist of list (point_x, point_y), this script will output the intersection of two street, it it exists
---
 line_segment_intersection.py | 71 ++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 line_segment_intersection.py

diff --git a/line_segment_intersection.py b/line_segment_intersection.py
new file mode 100644
index 0000000..a58ed0a
--- /dev/null
+++ b/line_segment_intersection.py
@@ -0,0 +1,71 @@
+# author 	: jianbin.hong.cn@gmail.com
+# date		: 2015/10/13
+
+import sys
+
+class Street(object):
+	"""
+	"""
+	start_point = None
+	end_point 	= None
+	points 		= None
+
+	def __init__(self, points):
+		"""
+		Assume each street have more than two points
+		"""
+		assert type(points) is list
+		assert len(points) > 1
+		assert type(points[0]) is tuple
+
+		self.start_point = points[0]
+		self.end_point = points[-1]
+		self.points = points
+
+	def _intersect_with_another_street(self, another_street):
+		"""
+		"""
+
+		def det(A, B):
+			"""
+			"""
+			return A[0] * B[1] - B[0] * A[1]
+
+		assert type(another_street) is Street
+		intersection_point = set()
+		for i in range(1, len(self.points)):
+			A1 = self.points[i - 1]
+			A2 = self.points[i]
+
+			for j in range(1, len(another_street.points)):
+				B1 = another_street.points[j - 1]
+				B2 = another_street.points[j]
+
+				diff1 	= (B1[0] - A1[0], B1[1] - A1[1])
+
+				r 		= (A2[0] - A1[0], A2[1] - A1[1])
+				s 		= (B2[0] - B1[0], B2[1] - B1[1])
+				rs		= det(r, s)
+
+				if rs == 0: continue
+				t 		= (det(diff1, s)) * 1.0 / rs
+				u 		= (det(diff1, r)) * 1.0 / rs
+				if u >= 0 and u <= 1 and t >= 0 and t <= 1: 
+					point = (A1[0] + t * r[0], A1[1] + t * r[1])
+					intersection_point.add(point)
+
+		if len(intersection_point):
+			return True, intersection_point
+
+		return False, None
+
+if __name__ == "__main__":
+	a = Street([(1, -2), (2, -1), (6, 0)])
+	b = Street([(2, -2), (2, 2)])
+	c = Street([(-2, 0), (6, 2)])
+	d = Street([(4, -2), (4, 2)])
+	e = Street([(5, -1), (5, 2)])
+	print a._intersect_with_another_street(b)
+	print a._intersect_with_another_street(c)
+	print a._intersect_with_another_street(d)
+	print a._intersect_with_another_street(e)