Find the number of rectangles from a given set of coordinates

Question

I need to find the maximum number of rectangles from a given set of coordinates.

Consider the following coordinates specified in the coordinate system XY 3 10, 3 8, 3 6, 3 4, 3 0, 6 0, 6 4, 6 8, 6 10,

How can I find if the following coordinates form a rectangle (3,0) (3,4) (6,4) (6,0)

Runtime Limit: 0.1s

thanks

Answer 1

, (x1, y1) (x2, y2) angular. (x1, y2) (x2, y1) , angular. , , angular, 2.

angular, X Y.

C++:

answer = 0;
set<pair<int, int>> points;

for(auto i=points.begin(); i!=std::prev(points.end()); i++)
{
    for(auto j=i+1; j!=points.end(); j++)
    {
        pair<int, int> p1 = *i;
        pair<int, int> p2 = *j;
        pair<int, int> p3 = make_pair(p1.first, p2.second);
        pair<int, int> p4 = make_pair(p2.first, p1.second);
        if(points.find(p3) != points.end() && points.find(p4) != points.end())
            ++answer;
    }
}

return answer/2;

Answer 2

"y", "x". :

3: [0,4,6,8,10]
6: [0,4,8,10]

: [0,4,8,10]

:

[0,4] => (3,0), (3,4), (6,0), (6,4)
[0,8] => (3,0), (3,8), (6,0), (6,8)
[4,8] => (3,4), (3,8), (6,4), (6,8)
...

, , x, y.

Answer 3

, 4 :

• . .
• .

[0] = a [1], a [2] = a [3], a [4] = a [5]

Answer 4

,

, , .. .

, . , , .

, . , , , .