Merge pull request #3619 from tylerw/tw/challenge-101

Challenge 101

1 files changed, 41 insertions, 0 deletions

diff --git a/challenge-101/tyler-wardhaugh/python/ch-2.py b/challenge-101/tyler-wardhaugh/python/ch-2.py
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+++ b/challenge-101/tyler-wardhaugh/python/ch-2.py
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+#!/usr/bin/env python3
+"""Challenge 101, Task 2"""
+
+import sys
+
+
+DEFAULT_INPUT = [[0, 1], [1, 0], [2, 2]]
+
+
+def contains_origin(triangle):
+    """Determine if the triangle formed by the given three points cover the (0,0)
+    origin on a 2D plane, using the Barycentric Coordinate Sytem method from
+    https://totologic.blogspot.com/2014/01/accurate-point-in-triangle-test.html"""
+    (x1, y1), (x2, y2), (x3, y3) = triangle
+
+    denominator = (y2 - y3) * (x1 - x3) + (x3 - x2) * (y1 - y3)
+    A = ((y2 - y3) * (0 - x3) + (x3 - x2) * (0 - y3)) / denominator
+    B = ((y3 - y1)*(0 - x3) + (x1 - x3)*(0 - y3)) / denominator
+    C = 1 - A - B
+
+    return all(0 <= x <= 1 for x in [A, B, C])
+
+
+def main(args=None):
+    """Run the task"""
+    if args is None:
+        args = sys.argv[1:]
+
+    triangle = None
+    if args:
+        import json
+        triangle = json.loads(args[0])
+    else:
+        triangle = DEFAULT_INPUT
+
+    result = 1 if contains_origin(triangle) else 0
+    print(result)
+
+
+if __name__ == '__main__':
+    sys.exit(main())