Merge pull request #775 from AlgorithmWithGod/Ukj0ng

[20250830] BOJ / P5 / 도로포장 / 한종욱

Author: ShinHeeEul

Ukj0ng/202508/30 BOJ P5 도로포장.md

@@ -0,0 +1,95 @@
+```
+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 final long INF = (long) 5e10 + 10;
+    private static List<Node>[] graph;
+    private static long[][] dist;
+    private static int N, M, K;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        dijkstra(1);
+        long answer = INF;
+        for (int i = 0; i <= K; i++) {
+            answer = Math.min(answer, dist[N][i]);
+        }
+        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());
+        M = Integer.parseInt(st.nextToken());
+        K = Integer.parseInt(st.nextToken());
+
+        graph = new List[N+1];
+        dist = new long[N+1][K+1];
+
+        for (int i = 1; i <= N; i++) {
+            graph[i] = new ArrayList<>();
+        }
+
+        for (int i = 1; i <= M; i++) {
+            st = new StringTokenizer(br.readLine());
+            int start = Integer.parseInt(st.nextToken());
+            int end = Integer.parseInt(st.nextToken());
+            int cost = Integer.parseInt(st.nextToken());
+
+            graph[start].add(new Node(end, cost));
+            graph[end].add(new Node(start, cost));
+        }
+    }
+
+    private static void dijkstra(int start) {
+        PriorityQueue<Node> pq = new PriorityQueue<>((o1, o2) -> Long.compare(o1.cost, o2.cost));
+        for (int i = 1; i <= N; i++) {
+            Arrays.fill(dist[i], INF);
+        }
+        dist[start][0] = 0;
+        pq.add(new Node(start, dist[start][0], 0));
+
+        while (!pq.isEmpty()) {
+            Node current = pq.poll();
+
+            if (current.cost > dist[current.dest][current.pavement]) continue;
+
+            for (Node next : graph[current.dest]) {
+                if (current.pavement+1 <= K && dist[current.dest][current.pavement]< dist[next.dest][current.pavement+1]) {
+                    dist[next.dest][current.pavement+1] = dist[current.dest][current.pavement];
+                    pq.add(new Node(next.dest, dist[next.dest][current.pavement+1], current.pavement+1));
+                }
+
+                if (dist[current.dest][current.pavement] + next.cost < dist[next.dest][current.pavement]) {
+                    dist[next.dest][current.pavement] = dist[current.dest][current.pavement] + next.cost;
+                    pq.add(new Node(next.dest, dist[next.dest][current.pavement], current.pavement));
+                }
+            }
+        }
+    }
+
+    static class Node {
+        int dest;
+        long cost;
+        int pavement;
+
+        Node (int dest, long cost) {
+            this.dest = dest;
+            this.cost = cost;
+            this.pavement = 0;
+        }
+
+        Node (int dest, long cost, int pavement) {
+            this.dest = dest;
+            this.cost = cost;
+            this.pavement = pavement;
+        }
+    }
+}
+```