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Feature: Added Algorithm to count the number of triangles that can be created when provided with a list of coordinates. #1340

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Feature: Added Algorithm to count the number of triangles that can be created when provided with a list of coordinates. #1340

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30 changes: 30 additions & 0 deletions HowManyTriangles/HowManyTriangles.py
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# Given an array of cartesian coordinates, how many triangles can be successfully created?

import itertools

def countTriangles(coords):
count = 0
for comb in itertools.combinations(coords, 3):
if (not isCollinear(*comb)):
count += 1
return count

def isCollinear(p1,p2,p3):
# If all x or all y are the same you have a straight line
if (p1[0] == p2[0] and p1[0] == p3[0]) or \
(p1[1] == p2[1] and p1[1] == p3[1]):
return True

# Calculate gradients for points
m1 = (p1[1] - p2[1])/(p1[0] - p2[0]) if((p1[0] - p2[0]) != 0) else 0
m2 = (p1[1] - p3[1])/(p1[0] - p3[0]) if((p1[0] - p3[0]) != 0) else 0

# If the gradients m1 & m2 are the same, you have a linear line
return m1 == m2

COORDS = [[0,0], [1,0], [2,0], [3,0],
[1,1], [2,1],
[0,2], [1,2], [2,2], [3,2]]

triangleCount = countTriangles(COORDS)
print(f"The coordinates provided can be used to create {triangleCount} unique triangles")