每日一题-LeetCode1037-有效的回旋镖

原题链接

叉乘结果为0，说明共线，否则说明不共线
三个向量的叉乘太麻烦了，换成两个计算

class Solution {
public:
    bool isBoomerang(vector>& points) {
        int x1 = points[0][0], y1 = points[0][1];
        int x2 = points[1][0], y2 = points[1][1];
        int x3 = points[2][0], y3 = points[2][1];
        int a = x2 - x1, b = y2 - y1;
        int c = x3 - x1, d = y3 - y1;
        if(a * d - b * c == 0)  return false;
        return true;
    }
};