finding all closest point pairs if multiple closest pairs exist - c++

Question

The following code is for finding the closest point pairs problem in Introduction to Programming with C++ liang textbook. and I'm trying to edit it so it can find all closest point pairs if multiple closest pairs exist.
#include <iostream>
#include <cmath>
using namespace std;
/** Compute the distance between two points (x1, y1) and (x2, y2) */
double getDistance(double x1, double y1, double x2, double y2)
{
return sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
}
int main()
{
const int NUMBER_OF_POINTS = 8;
// Each row in points represents a point
double points[NUMBER_OF_POINTS][2];
cout << "Enter " << NUMBER_OF_POINTS << " points: ";
for (int i = 0; i < NUMBER_OF_POINTS; i++)
cin >> points[i][0] >> points[i][1];
// p1 and p2 are the indices in the points array
int p1 = 0, p2 = 1; // Initial two points
double shortestDistance = getDistance(points[p1][0], points[p1][1],
points[p2][0], points[p2][1]); // Initialize
// Compute distance for every two points
for (int i = 0; i < NUMBER_OF_POINTS; i++)
{
for (int j = i + 1; j < NUMBER_OF_POINTS; j++)
{
double distance = getDistance(points[i][0], points[i][1],
points[j][0], points[j][1]); // Find distance
if (shortestDistance > distance)
{
p1 = i; // Update p1
p2 = j; // Update p2
shortestDistance = distance; // Update shortestDistance
}
}
}
// Display result
cout << "The closest two points are " <<
"(" << points[p1][0] << ", " << points[p1][1] << ") and (" <<
points[p2][0] << ", " << points[p2][1] << ")";
return 0;
}
I solved it by using a new array, distance-points , and save the distance with the points pair whenever the distance is calculated, after that I loop over the new array and print out the shortest distance, but I think there is smarter solution for sure, Im quite new in programming :)
double distance_points[28][5];
int f = 0 ;
// Compute distance for every two points
for (int i = 0; i < NUMBER_OF_POINTS; i++)
{
for (int j = i + 1; j < NUMBER_OF_POINTS; j++)
{
double distance = getDistance(points[i][0], points[i][1],
points[j][0], points[j][1]); // Find distance
distance_points[f][0] = distance;
distance_points[f][1] = points[i][0];
distance_points[f][2] = points[i][1];
distance_points[f][3] = points[j][0];
distance_points[f][4] = points[j][1];
f++;
}
}

Answer 1

You may change your algorithm to stock results in vector:
std::vector<int> p1, p2;
double shortestDistance = getDistance(points[p1][0], points[p1][1],
points[p2][0], points[p2][1]); // Initialize
for (int i = 0; i < NUMBER_OF_POINTS; i++) {
for (int j = i + 1; j < NUMBER_OF_POINTS; j++) {
const double distance = getDistance(points[i][0], points[i][1],
points[j][0], points[j][1]);
if (shortestDistance >= distance) {
if (shortestDistance > distance) {
p1.clear();
p2.clear();
shortestDistance = distance; // Update shortestDistance
}
p1.push_back(i); // Update p1
p2.push_back(j); // Update p2
}
}
}