Leetcode – Valid Boomerang Solution

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The “Valid Boomerang” problem is an exciting exploration into the realm of geometric principles and their application in algorithmic challenges. Understanding the properties and conditions that define specific geometric shapes can greatly simplify seemingly complex problems. This article aims to present a detailed analysis of the “Valid Boomerang” problem, its underlying principles, various solution strategies, and Python implementations.

Table of Contents:

  1. Problem Statement
  2. Exploring the Concept of Boomerangs in Geometry
  3. Key Insights to Solve the Problem
  4. Python Implementations
  5. Testing the Solution
  6. Concluding Remarks

1. Problem Statement:

A boomerang is defined as a tuple of points (i.e., a list of three points) that are distinct and not in a straight line. Given a list of three points in the plane, return whether these points form a boomerang.


Input: [[1,1],[2,3],[3,2]]
Output: true

2. Exploring the Concept of Boomerangs in Geometry:

A boomerang, in this context, essentially means that the three given points should not be collinear. Collinearity in a plane refers to the condition where three or more points lie on a straight line.

3. Key Insights to Solve the Problem:

  1. Distinct Points: The three points should be distinct. If any two points are the same, it’s not a boomerang.
  2. Slope Principle: For three points to be collinear, the slopes they form with each other should be equal. ​​If the slopes formed by the pairs of points are the same, then the points are collinear.
  3. Avoiding Division: To prevent the division by zero error (in case the denominators in the slope formula are zero), we can compare the products of the differences instead of the ratios.

4. Python Implementations:

Slope Comparison Approach:

def isBoomerang(points):
    # Calculate differences to avoid repeated subtraction
    dx1 = points[1][0] - points[0][0]
    dy1 = points[1][1] - points[0][1]
    dx2 = points[2][0] - points[1][0]
    dy2 = points[2][1] - points[1][1]

    # Check for distinct points
    if points[0] == points[1] or points[1] == points[2] or points[0] == points[2]:
        return False

    # Check for collinearity using product of differences (avoiding division)
    return dy1 * dx2 != dy2 * dx1

5. Testing the Solution:

It’s crucial to test the solution on various test cases to ensure accuracy:

print(isBoomerang([[1,1],[2,3],[3,2]]))  # Expected output: True
print(isBoomerang([[1,1],[2,2],[3,3]]))  # Expected output: False (Collinear)
print(isBoomerang([[1,1],[2,2],[2,2]]))  # Expected output: False (Same points)

6. Concluding Remarks:

The “Valid Boomerang” problem serves as a testament to the utility of geometric principles in algorithmic challenges. The solution, while rooted in the basic slope formula, teaches an important lesson on avoiding pitfalls like division by zero. Moreover, this problem highlights how a seemingly intricate question can have a simple and elegant solution. As always, a deeper understanding of the problem domain, in this case, geometry, proves invaluable in crafting efficient solutions to computational problems.

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