Merge pull request #187 from AlgorithmWithGod/suyeun84

[20250226] BOJ / 골드3 / 웜홀 / 김수연

Author: ShinHeeEul

suyeun84/202502/26 BOJ G3 웜홀.md

@@ -0,0 +1,77 @@
+```java
+import java.util.*;
+import java.io.*;
+
+public class boj1865 {
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st;
+	
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static int nextInt() {return Integer.parseInt(st.nextToken());}
+	static void bwEnd() throws Exception {bw.flush(); bw.close();}
+	static ArrayList<Road> road;
+	static int N;
+
+	public static void main(String[] args) throws Exception {
+		nextLine();
+		int TC = nextInt();
+		for (int tc = 0; tc < TC; tc++) {
+			nextLine();
+			N = nextInt(); //지점의 수
+			int M = nextInt(); //도로의 갯수
+			int W = nextInt(); //웜홀의 갯수
+			road = new ArrayList<>(N+1);
+
+			int S, E, T;
+			for (int i = 0 ; i < M+W; i++) {
+				nextLine();
+				S = nextInt();
+				E = nextInt();
+				T = nextInt();
+				if (i < M) {
+					road.add(new Road(S, E, T));
+					road.add(new Road(E, S, T));
+				} else {
+					road.add(new Road(S, E, -1*T));
+				}
+			}
+			
+			if (bfs()) bw.write("YES"+"\n");
+			else bw.write("NO"+"\n");
+		}
+		bwEnd();
+	}
+	
+	// 음수 사이클 존재하면 true 반환
+	static boolean bfs() {
+		int[] time = new int[N+1];
+		Arrays.fill(time, 10001);
+		time[1] = 0;
+		
+		for (int i = 0; i < N; i++) { //N-1번 반복 + N번째 처리
+			for (int j = 0; j < road.size(); j++) { //간선 확인
+				Road r = road.get(j);
+				if (i == N-1) {
+					if (time[r.e] > time[r.s]+r.t) return true;
+					continue;
+				}
+				time[r.e] = Math.min(time[r.e], time[r.s]+r.t);
+			}
+		}
+		return false;
+	}
+
+	static class Road {
+		int s;
+		int e;
+		int t;
+		public Road(int s, int e, int t) {
+			this.s = s;
+			this.e = e;
+			this.t = t;
+		}
+	}
+}
+
+```