[20251019] BOJ / G4 / 비밀 모임 / 이준희

JHLEE325/202510/19 BOJ G4 비밀 모임.md

@@ -0,0 +1,108 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static class Node implements Comparable<Node> {
+        int to, cost;
+
+        public Node(int t, int c) {
+            this.to = t;
+            this.cost = c;
+        }
+
+        @Override
+        public int compareTo(Node o) {
+            return this.cost - o.cost;
+        }
+    }
+
+    static final int INF = 987654321;
+    static List<Node>[] graph;
+    static int N, M, K;
+    static int[] friends;
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+
+        int T = Integer.parseInt(br.readLine());
+        StringBuilder sb = new StringBuilder();
+
+        while (T-- > 0) {
+            st = new StringTokenizer(br.readLine());
+            N = Integer.parseInt(st.nextToken());
+            M = Integer.parseInt(st.nextToken());
+
+            graph = new ArrayList[N + 1];
+            for (int i = 1; i <= N; i++) graph[i] = new ArrayList<>();
+
+            for (int i = 0; i < M; i++) {
+                st = new StringTokenizer(br.readLine());
+                int a = Integer.parseInt(st.nextToken());
+                int b = Integer.parseInt(st.nextToken());
+                int d = Integer.parseInt(st.nextToken());
+                graph[a].add(new Node(b, d));
+                graph[b].add(new Node(a, d));
+            }
+
+            K = Integer.parseInt(br.readLine());
+            friends = new int[K];
+            st = new StringTokenizer(br.readLine());
+            for (int i = 0; i < K; i++) friends[i] = Integer.parseInt(st.nextToken());
+
+            int[][] dist = new int[K][N + 1];
+            for (int i = 0; i < K; i++) {
+                dist[i] = dijkstra(friends[i]);
+            }
+
+            int minSum = INF;
+            int room = 0;
+
+            for (int i = 1; i <= N; i++) {
+                int total = 0;
+                for (int j = 0; j < K; j++) {
+                    total += dist[j][i];
+                }
+
+                if (total < minSum) {
+                    minSum = total;
+                    room = i;
+                }
+            }
+
+            sb.append(room).append('\n');
+        }
+
+        System.out.print(sb.toString());
+    }
+
+    public static int[] dijkstra(int start) {
+        boolean[] check = new boolean[N + 1];
+        int[] dist = new int[N + 1];
+
+        Arrays.fill(dist, 987654321);
+        dist[start] = 0;
+
+        PriorityQueue<Node> pq = new PriorityQueue<>();
+        pq.offer(new Node(start, 0));
+
+        while (!pq.isEmpty()) {
+            int cur = pq.poll().to;
+
+            if (check[cur])
+                continue;
+            check[cur] = true;
+
+            for (Node next : graph[cur]) {
+                if (dist[next.to] > dist[cur] + next.cost) {
+                    dist[next.to] = dist[cur] + next.cost;
+                    pq.offer(new Node(next.to, dist[next.to]));
+                }
+            }
+        }
+
+        return dist;
+    }
+}```