Fix point-to-line distance calculation for vertical lines

[Copilot]

The existing implementation used slope-intercept form, causing division by zero for vertical lines (dx=0), resulting in NaN output.

Changes

• Replaced slope-intercept method with cross product formula: distance = |(B-A) × (A-P)| / |B-A|
• Removes TODO comment and completes implementation

Before/After

// Before: fails on vertical lines
double dx = L.point_A.x - L.point_B.x;
double dy = L.point_A.y - L.point_B.y;
double k = dy / dx;  // division by zero if dx=0
double b1 = L.point_A.y - k*L.point_A.x;
double distance = fabs(k*P.x - P.y + b1) / sqrt(k*k + 1);

// After: handles all cases
double dx = L.point_B.x - L.point_A.x;
double dy = L.point_B.y - L.point_A.y;
double crossProduct = fabs(dx * (L.point_A.y - P.y) - (L.point_A.x - P.x) * dy);
double lineLength = sqrt(dx * dx + dy * dy);
double distance = crossProduct / lineLength;

Test case echo "1 0 0 0 0 1" | ./program now outputs 1.00 instead of nan.

Original prompt

处理 TODO: 计算点P到直线L的距离 (来自 niuke/practice/noob/noob72 点到直线距离/1.cpp)

Created from VS Code via the GitHub Pull Request extension.

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[Copilot]

Pull request overview

This is a work-in-progress pull request that implements the calculation of the distance from a point to a line in a C++ competitive programming solution. The PR addresses a TODO comment by adding the mathematical implementation for this geometric calculation.

Key Changes (Inferred):

• Implementation of the getDistance function to calculate point-to-line distance
• Uses slope-intercept form approach with the formula |kx - y + b| / sqrt(k² + 1)

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[tkzzzzzz6]

good