题解 | 点到直线距离

题干解读：给出了一个点和一条直线的位置信息，要求输出他们的举例

思路：先由直线中两点确定这个直线的一般式，再由一般式来写两点间的距离公式，最后return即可.

#include <bits/stdc++.h>
using namespace std;

struct point{
    double x,y;
    point(double A,double B){
        x=A,y=B;
    }
    point() = default;
};

struct line{
    point point_A,point_B;
    line(point A,point B){
        point_A = A,point_B = B;
    }
    line() = default;
};

double getDistance(point P, line L){
    double C1,C2,C3;//分别对应直线x前，y前系数和常数.
    double dis;

    C1 = (double)(L.point_A.y -L.point_B.y);
    C2 = (double)(-(L.point_A.x - L.point_B.x));
    C3 = -C2*L.point_A.y-C1*L.point_A.x;
    dis = fabs(C1*P.x +C2*P.y+C3)/sqrt(C1*C1 + C2*C2);
    
    
    return dis;
}















































































































int main(){
    int a, b, sx, sy, tx, ty;
    cin >> a >> b >> sx >> sy >> tx >> ty;
    point A(sx, sy), B(tx, ty), C(a, b);
    line L(A, B);
    printf("%.2lf", getDistance(C, L));
    return 0;
}