[20250820] BOJ / G3/ 파티 / 이종환

Author: 0224LJH

0224LJH/202508/20 BOJ 파티.md

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+``` java
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.*;
+
+
+public class Main {
+	static final int MAX = Integer.MAX_VALUE/2;
+
+	static PriorityQueue<Node> nodePq = new PriorityQueue<>();
+	static PriorityQueue<Edge> edgePq = new PriorityQueue<>();
+	static Node[] nodes;
+	static boolean[] visited;
+	static int[] dis,totalSum;
+	
+	static int nodeCnt, edgeCnt, target, ans;
+	
+
+	
+	static class Node implements Comparable<Node>{
+		int num;
+		int dis;
+		List<Edge> edges;
+		
+		public Node(int num) {
+			this.num = num;
+			edges = new ArrayList<>();
+		}
+		
+		public int compareTo(Node n) {
+			return this.dis - n.dis;
+		}
+	}
+	
+	static class Edge implements Comparable<Edge>{
+		int to;
+		int weight;
+		
+		public Edge(int to, int weight) {
+			this.to = to;
+			this.weight = weight;
+		}
+		
+		@Override
+		public int compareTo(Edge e) {
+			return this.weight - e.weight;
+		}
+		
+		
+	}
+	
+	public static void main(String[] args) throws IOException {
+		init();
+		process();
+		print();
+	}
+	
+	public static void init() throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StringTokenizer st = new StringTokenizer(br.readLine());
+		
+		nodeCnt = Integer.parseInt(st.nextToken());
+		edgeCnt = Integer.parseInt(st.nextToken());
+		target = Integer.parseInt(st.nextToken());
+		ans = 0;
+		
+		nodes = new Node[nodeCnt+1];
+		totalSum = new int[nodeCnt+1];
+		for (int i = 1; i <= nodeCnt; i++) {
+			nodes[i] = new Node(i);
+		}
+		
+		for (int i = 0; i < edgeCnt; i++) {
+			st = new StringTokenizer(br.readLine());
+			int from = Integer.parseInt(st.nextToken());
+			int to = Integer.parseInt(st.nextToken());
+			int weight = Integer.parseInt(st.nextToken());
+			nodes[from].edges.add(new Edge(to,weight));
+		}
+		
+	}
+	
+	public static void process() {
+		for (int i = 1; i <= nodeCnt; i++) {
+			makeMinDis(i);
+			if (i == target) {
+				for (int j = 1; j <= nodeCnt; j++) {
+					totalSum[j] += dis[j];
+				}
+				
+			} else {
+				totalSum[i] += dis[target];
+			}
+		}
+		
+		for (int i = 1; i <= nodeCnt; i++) {
+			ans = Math.max(ans,totalSum[i]);
+		}
+	}
+	
+	
+	private static void makeMinDis(int start) {
+		
+		dis = new int[nodeCnt+1];
+		visited = new boolean[nodeCnt+1];
+		Arrays.fill(dis, MAX);
+		dis[start] = 0;
+		
+		nodePq.clear();
+		nodePq.add(nodes[start]);
+		
+		while (!nodePq.isEmpty()) {
+			Node n = nodePq.poll();
+			int from = n.num;
+            
+            if (from != start && from == target) break;
+			
+			if (visited[from]) continue;
+			visited[from] = true;
+			
+			edgePq.clear();
+			edgePq.addAll(n.edges);
+			
+			while (!edgePq.isEmpty()) {
+				Edge e = edgePq.poll();
+				
+				if (visited[e.to]) continue;
+				int newDis = dis[from] + e.weight;
+				if (newDis < dis[e.to]) {
+					dis[e.to] = newDis;
+                    nodes[e.to].dis = dis[e.to];
+					nodePq.add(nodes[e.to]);
+				}
+				
+			}
+		}
+		
+	}
+
+	public static void print() {
+		System.out.println(ans);
+	}
+}
+```