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Solution: Erect the Fence

Explore the solution for enclosing trees with the shortest fence by computing the convex hull of their coordinates. Learn to apply the Monotone Chain algorithm to construct the convex boundary efficiently, understand orientation checks using cross products, and grasp the time and space complexity of this geometric approach.

Statement

You are given an array of points, trees, where trees[i] = [xᵢ, yᵢ] represents the location of a tree on a 2D plane. Your goal is to enclose all the trees using the shortest possible length of rope, forming a fence around the garden. A garden is considered well-fenced if every tree lies inside or on the boundary of the fence (i.e., the fence forms the convex hullThis is the smallest convex shape, completely encloses a set of points. of all the points).

Return the coordinates of the trees that lie exactly on the fence perimeter. You can return the answer in any order.

Constraints:

  • 11 \leq trees.length 300\leq 300

  • trees[i].length == 22

  • 00 \leq xi, yi 100\leq ...