[20250901] BOJ / G3 / 웜홀 / 이인희

LiiNi-coder/202509/01 BOJ 웜홀.md

@@ -0,0 +1,83 @@
+```java
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.StringTokenizer;
+
+public class Main {
+    private static BufferedReader br;
+    private static StringBuilder sb;
+    private static StringTokenizer st;
+    private static int n;
+    private static int m;
+    private static int w;
+    private static class Edge {
+        int from;
+        int to;
+        int weight;
+        public Edge(int from, int to, int weight) {
+            this.from = from;
+            this.to = to;
+            this.weight = weight;
+        }
+    }
+
+    private static ArrayList<Edge> edges;
+
+    public static void main(String[] args) throws IOException {
+        br = new BufferedReader(new InputStreamReader(System.in));
+        sb = new StringBuilder();
+
+        int tc = Integer.parseInt(br.readLine());
+        while (tc-- > 0) {
+            st = new StringTokenizer(br.readLine());
+            n = Integer.parseInt(st.nextToken());
+            m = Integer.parseInt(st.nextToken());
+            w = Integer.parseInt(st.nextToken());
+
+            edges = new ArrayList<>();
+            for (int i = 0; i < m; i++) {
+                st = new StringTokenizer(br.readLine());
+                int s = Integer.parseInt(st.nextToken());
+                int e = Integer.parseInt(st.nextToken());
+                int t = Integer.parseInt(st.nextToken());
+                edges.add(new Edge(s, e, t));
+                edges.add(new Edge(e, s, t));
+            }
+
+            for (int i = 0; i < w; i++) {
+                st = new StringTokenizer(br.readLine());
+                int s = Integer.parseInt(st.nextToken());
+                int e = Integer.parseInt(st.nextToken());
+                int t = Integer.parseInt(st.nextToken());
+                edges.add(new Edge(s, e, -t));
+            }
+            if (bellmanFord()) {
+                sb.append("YES\n");
+            } else {
+                sb.append("NO\n");
+            }
+        }
+
+        System.out.print(sb.toString());
+    }
+
+    private static boolean bellmanFord() {
+        int[] dist = new int[n + 1];
+        for (int i = 1; i < n; i++) {
+            for (Edge edge : edges) {
+                if (dist[edge.to] > dist[edge.from] + edge.weight) {
+                    dist[edge.to] = dist[edge.from] + edge.weight;
+                }
+            }
+        }
+        for (Edge edge : edges) {
+            if (dist[edge.to] > dist[edge.from] + edge.weight) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
+```