LeetCode 593 Valid Squares [Math] HERODING's Road to LeetCode

解题思路：
A math problem that is not very difficult,有好几种解决方法,The simplest is to directly determine whether it is a square or not,That is, only four sides are equal,And any two sides are parallel or perpendicular,A simpler way to judge is that any three points are a right triangle,代码如下：

class Solution {
    
public:
    bool validSquare(vector<int>& p1, vector<int>& p2, vector<int>& p3, vector<int>& p4) {
    
        return isRTriangle(p1, p2, p3) && isRTriangle(p1, p2, p4) && isRTriangle(p1, p3, p4) && isRTriangle(p2, p3, p4);
    }

    bool isRTriangle(vector<int>& p1, vector<int>& p2, vector<int>& p3) {
    
        int l1 = (p1[0] - p2[0]) * (p1[0] - p2[0]) + (p1[1] - p2[1]) * (p1[1] - p2[1]);
        int l2 = (p1[0] - p3[0]) * (p1[0] - p3[0]) + (p1[1] - p3[1]) * (p1[1] - p3[1]);
        int l3 = (p2[0] - p3[0]) * (p2[0] - p3[0]) + (p2[1] - p3[1]) * (p2[1] - p3[1]);
        if(l1 > l2 && l2 == l3 && l1 == l2 + l3 ||
            l2 > l1 && l1 == l3 && l2 == l1 + l3 ||
            l3 > l1 && l1 == l2 && l3 == l1 + l2) {
    
                return true;
            }
        return false;
    }
};