241111 Watering the Fields

private static class Point {
	int x;
	int y;

	public Point(int x, int y) {
		this.x = x;
		this.y = y;
	}
}

private static int n;
private static int threshold;
private static Point[] points;

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	StringTokenizer st = new StringTokenizer(br.readLine());

	n = Integer.parseInt(st.nextToken());
	threshold = Integer.parseInt(st.nextToken());
	points = new Point[n];

	for (int i = 0; i < n; i++) {
		st = new StringTokenizer(br.readLine());
		points[i] = new Point(Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken()));
	}

	System.out.println(findMST());
}

private static long findMST() {
	int[] minDistance = new int[n];
	boolean[] visited = new boolean[n];
	long totalCost = 0;

	for (int i = 0; i < n; i++) {
		minDistance[i] = Integer.MAX_VALUE;
	}

	int current = 0;
	for (int i = 0; i < n - 1; i++) {
		visited[current] = true;
		int nearest = -1;
		int minCost = Integer.MAX_VALUE;

		for (int j = 0; j < n; j++) {
			if (visited[j])
				continue;

			int cost = calculateCost(points[current], points[j]);
			minDistance[j] = Math.min(minDistance[j], cost);

			if (minDistance[j] < minCost) {
				minCost = minDistance[j];
				nearest = j;
			}
		}

		if (nearest == -1) {
			return -1;
		}

		totalCost += minCost;
		current = nearest;
	}

	return totalCost;
}

private static int calculateCost(Point p1, Point p2) {
	int distSquared = (p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y);
	return distSquared < threshold ? Integer.MAX_VALUE : distSquared;
}

출처:https://www.acmicpc.net/problem/10021