用qt写一个函数实现：输入三角形三个点，返回一条边长度，这条边长度和其他边长度差异最大，同时返回这条边顶点

非常感谢您的提问！以下是我为您提供的代码：

#include <QtMath>

struct Point {
    double x;
    double y;
};

double distance(Point p1, Point p2) {
    double dx = p1.x - p2.x;
    double dy = p1.y - p2.y;
    return qSqrt(dx * dx + dy * dy);
}

void findMaxDiffEdge(Point p1, Point p2, Point p3, double& maxDiff, Point& maxDiffVertex) {
    double d1 = distance(p1, p2);
    double d2 = distance(p2, p3);
    double d3 = distance(p3, p1);
    double diff1 = qAbs(d1 - d2);
    double diff2 = qAbs(d2 - d3);
    double diff3 = qAbs(d3 - d1);
    if (diff1 > diff2 && diff1 > diff3) {
        maxDiff = diff1;
        maxDiffVertex = p3;
    } else if (diff2 > diff1 && diff2 > diff3) {
        maxDiff = diff2;
        maxDiffVertex = p1;
    } else {
        maxDiff = diff3;
        maxDiffVertex = p2;
    }
}

int main() {
    Point p1 = {0, 0};
    Point p2 = {3, 0};
    Point p3 = {0, 4};
    double maxDiff;
    Point maxDiffVertex;
    findMaxDiffEdge(p1, p2, p3, maxDiff, maxDiffVertex);
    qDebug() << "Max difference: " << maxDiff << ", Vertex: (" << maxDiffVertex.x << ", " << maxDiffVertex.y << ")";
    return 0;
}

这个函数使用了 Qt 的数学库 qSqrt() 来计算两点之间的距离。它接受三个点作为参数，计算出三条边的长度，并找出其中长度差异最大的那条边，同时返回这条边的顶点。在这个例子中，我们使用了三个点 (0,0), (3,0) 和 (0,4) 来测试函数。