[20250727] BOJ / G4 / 타임머신 / 이준희

JHLEE325/202507/27 BOJ G4 타임머신.md

@@ -0,0 +1,73 @@
+```java
+import java.io.*;
+import java.util.*;
+
+class Edge {
+    int from, to, cost;
+
+    public Edge(int from, int to, int cost) {
+        this.from = from;
+        this.to = to;
+        this.cost = cost;
+    }
+}
+
+public class Main {
+    static final long INF = 987654321;
+    static int n, m;
+    static List<Edge> edges = new ArrayList<>();
+    static long[] dist;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+
+        st = new StringTokenizer(br.readLine());
+        n = Integer.parseInt(st.nextToken());
+        m = Integer.parseInt(st.nextToken());
+
+        dist = new long[n + 1];
+
+        for (int i = 0; i < m; i++) {
+            st = new StringTokenizer(br.readLine());
+            int from = Integer.parseInt(st.nextToken());
+            int to = Integer.parseInt(st.nextToken());
+            int cost = Integer.parseInt(st.nextToken());
+            edges.add(new Edge(from, to, cost));
+        }
+
+        if (!bellmanFord(1)) {
+            System.out.println(-1);
+        } else {
+            for (int i = 2; i <= n; i++) {
+                if (dist[i] == INF)
+                    System.out.println(-1);
+                else
+                    System.out.println(dist[i]);
+            }
+        }
+    }
+
+    static boolean bellmanFord(int start) {
+        Arrays.fill(dist, INF);
+        dist[start] = 0;
+
+        for (int i = 1; i < n; i++) {
+            for (Edge e : edges) {
+                if (dist[e.from] != INF && dist[e.to] > dist[e.from] + e.cost) {
+                    dist[e.to] = dist[e.from] + e.cost;
+                }
+            }
+        }
+
+        for (Edge e : edges) {
+            if (dist[e.from] != INF && dist[e.to] > dist[e.from] + e.cost) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}
+
+```