Minimum Area Rectangle II_1.cpp

struct Dot
{
    int x, y;
    
    Dot(int i, int j)
    {
        x = i;
        y = j;
    }
    
    bool operator==(const Dot& that)const
    {
        return x == that.x && y == that.y;
    }
};

struct Hasher
{
    size_t operator()(const Dot& point)const
    {
        string str = to_string(point.x) + ":" + to_string(point.y);
        return hash<string>()(str);
    }
};

class Solution {
public:
    double minAreaFreeRect(vector<vector<int>>& points) {
        int len = points.size();
        unordered_set<Dot, Hasher> set;
        for(auto& point : points)
        {
            Dot p(point[0], point[1]);
            set.insert(p);
        }
        double res = 40005 * 40005;
        for(int i = 0; i < len; ++i)
        {
            Dot p0(points[i][0], points[i][1]);
            for(int j = 0; j < len; ++j)
            {
                if(j == i)continue;
                Dot p1(points[j][0], points[j][1]);
                for(int k = j + 1; k < len; ++k)
                {
                    if(k== i)continue;
                    Dot p2(points[k][0], points[k][1]);
                    Dot p3(p1.x + p2.x - p0.x, p1.y + p2.y - p0.y);
                    if(set.find(p3) != set.end() && isPerpen(p0, p1, p2))
                    {
                        double e1 = getLen(p0, p1), e2 = getLen(p0, p2);
                        res = min(res, e1 * e2);
                    }
                }
            }
        }
        return res < 40005 * 40005? res : 0;
    }
    
private:
    bool isPerpen(const Dot& p0, const Dot& p1, const Dot& p2)
    {
        Dot vector1(p1.x - p0.x, p1.y - p0.y), vector2(p2.x - p0.x, p2.y - p0.y);
        return vector1.x * vector2.x + vector1.y * vector2.y == 0;
    }
    
    double getLen(const Dot& p0, const Dot& p1)
    {
        return sqrt(pow(p1.x - p0.x, 2) + pow(p1.y - p0.y, 2));
    }
};