diff --git "a/Ukj0ng/202601/09 BOJ G4 \353\221\220 \353\241\234\353\264\207 .md" "b/Ukj0ng/202601/09 BOJ G4 \353\221\220 \353\241\234\353\264\207 .md" new file mode 100644 index 00000000..8c3cccbf --- /dev/null +++ "b/Ukj0ng/202601/09 BOJ G4 \353\221\220 \353\241\234\353\264\207 .md" @@ -0,0 +1,83 @@ +``` +import java.io.*; +import java.util.*; + +public class Main { + private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); + private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out)); + private static List[] edges; + private static boolean[] visited; + private static int N, start, end; + + public static void main(String[] args) throws IOException { + init(); + + int answer = BFS(); + + bw.write(answer + "\n"); + bw.flush(); + bw.close(); + br.close(); + } + + private static void init() throws IOException { + StringTokenizer st = new StringTokenizer(br.readLine()); + N = Integer.parseInt(st.nextToken()); + start = Integer.parseInt(st.nextToken()); + end = Integer.parseInt(st.nextToken()); + + edges = new List[N+1]; + visited = new boolean[N+1]; + + for (int i = 1; i <= N; i++) { + edges[i] = new ArrayList<>(); + } + + for (int i = 1; i < N; i++) { + st = new StringTokenizer(br.readLine()); + int node1 = Integer.parseInt(st.nextToken()); + int node2 = Integer.parseInt(st.nextToken()); + int cost = Integer.parseInt(st.nextToken()); + edges[node1].add(new Edge(node2, cost)); + edges[node2].add(new Edge(node1, cost)); + } + } + + private static int BFS() { + Queue q = new ArrayDeque<>(); + visited[start] = true; + int result = 0; + // node, cost, max + q.add(new int[]{start, 0, 0}); + + while (!q.isEmpty()) { + int[] current = q.poll(); + + if (current[0] == end) { + result = current[1]-current[2]; + break; + } + + for (Edge edge : edges[current[0]]) { + if (visited[edge.dest]) continue; + visited[edge.dest] = true; + int cost = current[1] + edge.cost; + int max = Math.max(current[2], edge.cost); + q.add(new int[]{edge.dest, cost, max}); + } + } + + return result; + } + + static class Edge { + int dest; + int cost; + + public Edge(int dest, int cost) { + this.dest = dest; + this.cost = cost; + } + } +} +```