| Mines HSPC 2025 Open Division |
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| Finished |
This year, Blaster wants to make a grand exit from graduation, and what better way to do so than by launching himself out of a cannon? Blaster's stunt can be modeled as a path in the XY-plane where the cannon is positioned at the origin, $$$(0, 0)$$$, and can be aimed at any angle.
Suspended in the air are $$$n$$$ floating hoops, each represented as a vertical segment. The $$$i$$$-th hoop is located $$$x_i$$$ meters along the X-axis. The bottom of the hoop is positioned $$$a_i$$$ meters above the X-axis, and the top of the hoop is positioned $$$b_i$$$ meters above the X-axis.
Blaster, modeled as a single point, will follow a perfectly straight-line trajectory after launch (since he has conveniently disabled Earth's gravity for this stunt). He is considered to pass through a hoop if his trajectory intersects or touches at least one point on the vertical line segment between $$$(x_i, a_i)$$$ and $$$(x_i, b_i)$$$ (inclusive).
Your task is to determine the maximum number of hoops Blaster can pass through if you carefully choose the cannon's launch angle.
The first line contains a single integer $$$n$$$ $$$(1 \leq n \leq 10^5)$$$ — the number of hoops.
Each of the next $$$n$$$ lines contains three integers $$$x_i, a_i, b_i$$$ $$$(1 \leq x_i \leq 10^9, 0 \leq a_i \leq b_i \leq 10^9)$$$, describing the position and height range of the $$$i$$$-th hoop.
Print a single integer—the maximum number of hoops Blaster can pass through for an optimal choice of launch angle.
5 2 1 3 4 2 5 3 1 4 5 3 6 1 2 3
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