[Week04] BOJ 4386: 별자리 만들기

weekly/week04/BOJ_4386_별자리만들기/JAEHEE25.java

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+package week04.BOJ_4386_별자리만들기;
+
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+class BOJ4386 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int N = Integer.parseInt(br.readLine());
+        double[][] stars = new double[N][2];
+        for (int i = 0; i < N; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            stars[i][0] = Double.parseDouble(st.nextToken());
+            stars[i][1] = Double.parseDouble(st.nextToken());
+        }
+
+        ArrayList<Edge>[] edges = new ArrayList[N];
+        for (int i = 0; i < N; i++) {
+            edges[i] = new ArrayList<>();
+        }
+
+        //모든 거리 저장
+        for (int i = 0; i < N-1; i++) {
+            for (int j = i+1; j < N; j++) {
+                double dist = getDistance(stars[i][0], stars[i][1], stars[j][0], stars[j][1]);
+                edges[i].add(new Edge(j, dist));
+                edges[j].add(new Edge(i, dist));
+            }
+        }
+
+        PriorityQueue<Edge> pq = new PriorityQueue<>();
+        boolean[] visit = new boolean[N];
+        pq.add(new Edge(0, 0.0));
+
+        double total = 0.0;
+        while (!pq.isEmpty()) {
+            Edge poll = pq.poll();
+            if (visit[poll.num]) continue;
+            visit[poll.num] = true;
+            total += poll.dist;
+
+            for (Edge next : edges[poll.num]) {
+                if (!visit[next.num]) {
+                    pq.add(next);
+                }
+            }
+        }
+
+        System.out.printf("%.2f", total);
+    }
+
+    static double getDistance(double x1, double y1, double x2, double y2) {
+        return Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2));
+    }
+
+}
+
+class Edge implements Comparable<Edge> {
+    int num;
+    double dist;
+
+    Edge(int num, double dist) {
+        this.num = num;
+        this.dist = dist;
+    }
+
+    @Override
+    public int compareTo(Edge o) {
+         return Double.compare(this.dist, o.dist);
+    }
+}
+