Largest triangle area

Link: https://leetcode.com/problems/largest-triangle-area/

Solution:

DSA: math

Intuition
Not really much to this problem. Just try all points with a triple for loop with the formula for calculating area with coordinates:
area = abs(0.5*(x1*(y2-y3)+ x2*(y3-y1) + x3*(y1-y2))

Implementation

def largest_triangle(points):
	res = 0
	for i in range(len(points)):
		for j in range(i+1, len(points)):
			for k in range(j+1, len(points)):
				x1, y1 = points[i]
				x2, y2 = points[j]
				x3, y3 = points[k]
				area = abs(0.5*(x1*(y2-y3) + x2*(y3-y1) + x3*(y1-y2)))
				res = max(res, area)
	return res

Visual

Review 1
You need the formula. Memorize the above. x1, x2, x3 is the product outside the brackets and inside the brackets its (next_y - next_next_y). For x2, the next_y is y3 and next_next_y wraps around to y1. The ordering of y’s is important due to the non-commutative property of subtraction.

review