C++ hw1 solution

problem3.cc

#include <math.h>
#include <vector>
#include <iostream>
using namespace std;
struct point {
	float x, y;
	point(float xx, float yy) :x{ xx }, y{ yy } {}
};
ostream& operator <<(ostream &os, const point &p) {
	os << "(";
	os << p.x << "," << p.y << ")";
		return os;
}
struct Distance {
	float  virtual operator() (point a, point b) = 0;
};

struct Euclidean :Distance {

	float operator() (point a, point b) {
		float dist = (a.x - b.x)*(a.x - b.x) + (a.y - b.y)*(a.y - b.y);
		return sqrt(dist);
	}
};

struct Manhattan :Distance {
	float operator() (point a, point b) {
		float dist = abs(a.x - b.x) + abs(a.y - b.y);
		return dist;
	}
};

point closest(vector<point> &pnts, point q, Distance& d) {
	point p = pnts[0];
	float dist = d(p, q);
	float min_dist = dist;
	for (int i = 1; i < pnts.size(); i++) {
		dist = d(pnts[i], q);
		if (dist < min_dist) {
			min_dist = dist;
			p = pnts[i];
		}

	}
	return p;
}
template <typename D>
point closest(vector<point> &pnts, point q) {
	point p = pnts[0];
	float dist = D()(p, q);
	float min_dist = dist;
	for (int i = 1; i < pnts.size(); i++) {
		dist = D()(pnts[i], q);
		if (dist < min_dist) {
			min_dist = dist;
			p = pnts[i];
		}
	}
	return p;
}


int main() {
	vector<point> pnts{ point(10,20), point(1,1), point(2,2), point(3,3) };
	cout << closest(pnts, point(4, 4), Euclidean());
	cout << closest<Euclidean>(pnts, point(4, 4));
}