题解 | 三角形面积

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

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

struct triangle{
    point a,b,c;
    triangle(point A,point B,point C){
        a=A,b=B,c=C;
    }
    triangle() = default;
};

double getArea(triangle T){
    // TODO: 计算三角形T的面积（向量叉乘）
    int x1=T.a.x;
    int y1=T.a.y;
    int x2=T.b.x;
    int y2=T.b.y;
    int x3=T.c.x;
    int y3=T.c.y;
    int xab=x2-x1;
    int yab=y2-y1;
    int xac=x3-x1;
    int yac=y3-y1;
    double a=abs(xab*yac*1.0-yab*xac*1.0);
    return a/2;
}