[20251009] BOJ / P4 / K번째 최단경로 찾기 / 한종욱

Ukj0ng/202510/09 BOJ P4 K번째 최단경로 찾기.md

@@ -0,0 +1,84 @@
+```
+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 PriorityQueue<Long>[] dist;
+    private static List<Node>[] graph;
+    private static int n, m, k;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        dijkstra();
+
+        for (int i = 1; i <= n; i++) {
+            if (dist[i].size() < k) {
+                bw.write("-1" + "\n");
+            } else {
+                bw.write(dist[i].peek() + "\n");
+            }
+        }
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        n = Integer.parseInt(st.nextToken());
+        m = Integer.parseInt(st.nextToken());
+        k = Integer.parseInt(st.nextToken());
+
+        dist = new PriorityQueue[n+1];
+        graph = new List[n+1];
+
+        for (int i = 0; i <= n; i++) {
+            dist[i] = new PriorityQueue<>((o1, o2) -> Long.compare(o2, o1));
+            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());
+            long c = Long.parseLong(st.nextToken());
+
+            graph[a].add(new Node(b, c));
+        }
+    }
+
+    private static void dijkstra() {
+        PriorityQueue<Node> pq = new PriorityQueue<>((o1, o2) -> Long.compare(o1.cost, o2.cost));
+        dist[1].add(0L);
+        pq.add(new Node(1, 0L));
+
+        while (!pq.isEmpty()) {
+            Node current = pq.poll();
+
+            for (Node next : graph[current.dest]) {
+                long nCost = current.cost + next.cost;
+                if (dist[next.dest].size() < k) {
+                    dist[next.dest].add(nCost);
+                    pq.add(new Node(next.dest, nCost));
+                } else if (dist[next.dest].peek() > nCost) {
+                    dist[next.dest].poll();
+                    dist[next.dest].add(nCost);
+                    pq.add(new Node(next.dest, nCost));
+                }
+            }
+        }
+    }
+
+    static class Node {
+        int dest;
+        long cost;
+
+        Node (int dest, long cost) {
+            this.dest = dest;
+            this.cost = cost;
+        }
+    }
+}
+```