Closest 2 points in 2D space

ClosestPoint2D.cpp

// Example program
#include <iostream>
#include <string>
#include <vector>
#include <math.h>

using namespace std;

struct Point {
    int x;
    int y;
};

struct Result {
    Point a;
    Point b;
    int distance;
    
    void calcDistance() {
        int yD = b.y - a.y;
        int xD = b.x - a.x;
        
        distance = sqrt(yD * yD - xD * xD);
    }
};

Result findClosest(vector<Point>& points) {
    cout << points.size() << endl;
    if (points.size() == 3) {
        Result r;
        r.a = points[0];
        r.b = points[1];
        r.calcDistance();
        
        Result r2;
        r2.a = points[0];
        r2.b = points[1];
        r2.calcDistance();
        
        Result r3;
        r3.a = points[1];
        r3.b = points[2];
        r3.calcDistance();
        
        if (r.distance <= r2.distance) {
            if (r.distance <= r3.distance) {
                return r;
            } else {
                return r3;    
            }
        } else {
            if (r2.distance <= r3.distance) { return r2; } else { return r3; }
        }
    }
    
    if (points.size() == 2) {
        Result r;
        r.a = points[0];
        r.b = points[1];
        r.calcDistance();
        
        return r;
    }
    
    auto mid = points.begin() + (points.size() / 2);
    auto start = points.begin();
    auto end = points.end();
    
    vector<Point> leftSide(mid - start);
    copy(start, mid, leftSide.begin());
    
    vector<Point> rightSide(end - mid);
    copy(mid, end, rightSide.begin());
    
    Result leftRes = findClosest(leftSide);
    Result rightRes = findClosest(rightSide);
    
    if (leftRes.distance <= rightRes.distance) { return leftRes;} else { return rightRes; }
}

int main()
{
      vector<Point> points = {
        Point{1,1},
        Point{1,3},
        Point{3,7},
        Point{4,4},
        Point{6,9},
        Point{7,4},
        Point{8,2},
        Point{9,2}
      };
      
      Result r = findClosest(points);
      
      cout << "First point is: x=" << r.a.x << " and y=" << r.a.y << " and second point is with x=" << r.b.x << " and y=" << r.b.y << endl;
}