[20250715] BOJ / G4 / 서강그라운드 / 신동윤

Author: 03do-new30

03do-new30/202507/15 BOJ G4 서강그라운드.md

@@ -0,0 +1,80 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    static int n, m, r, maxItem;
+    static int[] items;
+    static List<int[]>[] graph;
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        n = Integer.parseInt(st.nextToken());
+        m = Integer.parseInt(st.nextToken());
+        r = Integer.parseInt(st.nextToken());
+        items = new int[n+1];
+        st = new StringTokenizer(br.readLine());
+        for (int i = 1; i <= n; i++) {
+            items[i] =  Integer.parseInt(st.nextToken());
+        }
+        graph = new List[n+1];
+        for (int i = 1; i <= n; i++) {
+            graph[i] = new ArrayList<>();
+        }
+        for (int i = 0; i < r; i++) {
+            st = new StringTokenizer(br.readLine());
+            int a =  Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+            int length = Integer.parseInt(st.nextToken());
+            graph[a].add(new int[] {b, length});
+            graph[b].add(new int[] {a, length});
+        }
+
+        for (int start = 1; start <= n; start++) {
+            dijkstra(start);
+        }
+        System.out.println(maxItem);
+        br.close();
+    }
+
+    private static void dijkstra(int start) {
+        PriorityQueue<int[]> pq = new PriorityQueue<>(new Comparator<int[]>() {
+            @Override
+            public int compare(int[] o1, int[] o2) {
+                return Integer.compare(o1[1], o2[1]);
+            }
+        });
+
+        int[] dist = new int[n+1];
+        for (int i = 1; i <= n; i++) {
+            dist[i] = Integer.MAX_VALUE;
+        }
+        dist[start] = 0;
+        pq.offer(new int[] {start, 0});
+
+        while (!pq.isEmpty()) {
+            int[] cur = pq.poll();
+            int curNode = cur[0];
+            for (int[] nex : graph[curNode]) {
+                int nextNode = nex[0];
+                int nextLength = nex[1];
+                if (dist[nextNode] > dist[curNode] + nextLength) {
+                    if (dist[curNode] + nextLength > m) {
+                        continue;
+                    }
+                    dist[nextNode] = dist[curNode] + nextLength;
+                    pq.offer(new int[]{nextNode, dist[nextNode]});
+                }
+            }
+        }
+        // 각 정점까지의 최단거리 구하기 완료
+        // start 정점에서 출발했을 떄, 얻을 수 있는 최대 아이템 개수 출력
+        int tmpItem = 0;
+        for (int i = 1; i <= n; i++) {
+            if (dist[i] == Integer.MAX_VALUE) { continue; }
+            tmpItem += items[i];
+        }
+        maxItem = Math.max(tmpItem, maxItem);
+    }
+}
+```