[Graph] baekjoon-11657

Author: Seogeurim

README.md

@@ -164,6 +164,7 @@
 | 01  |     | [Baekjoon-11724 연결 요소의 개수](./src/Graph/P11724) |      |
 | 02  |     | [Baekjoon-1707 이분 그래프](./src/Graph/P1707)        |      |
 | 03  |     | [Baekjoon-1753 최단경로](./src/Graph/P1753)        |   Dijkstra   |
+| 04  |     | [Baekjoon-11657 타임머신](./src/Graph/P11657)        |   Bellman-Ford   |
 
 ### Union-Find
 

src/Graph/P11657/Main.java

@@ -0,0 +1,62 @@
+package Graph.P11657;
+
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    final static int INF = Integer.MAX_VALUE;
+    static int N, M;
+    static Edge[] edges;
+    static long[] D;
+
+    public static void main(String[] args) throws Exception {
+        System.setIn(new FileInputStream("src/Graph/P11657/input.txt"));
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        edges = new Edge[M];
+        for (int i = 0; i < M; i++) {
+            st = new StringTokenizer(br.readLine());
+            int A = Integer.parseInt(st.nextToken());
+            int B = Integer.parseInt(st.nextToken());
+            int C = Integer.parseInt(st.nextToken());
+            edges[i] = new Edge(A, B, C);
+        }
+
+        D = new long[N+1];
+        Arrays.fill(D, INF); D[1] = 0;
+
+        boolean loop = false;
+        for (int i = 1; i <= N; i++) {
+            for (int j = 0; j < M; j++) {
+                Edge edge = edges[j];
+                if (D[edge.from] != INF && D[edge.to] > D[edge.from] + edge.time) {
+                    if (i == N) { loop = true; break; }
+                    D[edge.to] = D[edge.from] + edge.time;
+                }
+            }
+        }
+
+        if (loop) System.out.println(-1);
+        else {
+            for (int i = 2; i <= N; i++) {
+                if (D[i] == INF) System.out.println(-1);
+                else System.out.println(D[i]);
+            }
+        }
+    }
+
+    static class Edge {
+        int from, to, time;
+
+        public Edge(int from, int to, int time) {
+            this.from = from;
+            this.to = to;
+            this.time = time;
+        }
+    }
+}

src/Graph/P11657/README.md

@@ -0,0 +1,13 @@
+## [baekjoon-11657] 타임머신
+
+![image](https://user-images.githubusercontent.com/22045163/106625700-4328c580-65ba-11eb-95b4-9fd5a2761cc7.png)
+
+### 출력 초과 이슈
+
+> [11657번 - 타임머신 > 출력초과 문제 해결이 되었는데 이유를 모르겠습니다](https://www.acmicpc.net/board/view/55270)
+
+![image](https://user-images.githubusercontent.com/22045163/106625810-62275780-65ba-11eb-9ece-2a882f589424.png)
+
+음의 가중치가 허용되기 때문에 underflow 이슈를 고려해야 한다. 앞으로 이런 부분도 신경 써서 구현해야겠다.
+
+![image](https://user-images.githubusercontent.com/22045163/106625767-550a6880-65ba-11eb-8091-48feded9e2b6.png)

src/Graph/P11657/input.txt

@@ -0,0 +1,15 @@
+3 4
+1 2 4
+1 3 3
+2 3 -1
+3 1 -2
+
+3 4
+1 2 4
+1 3 3
+2 3 -4
+3 1 -2
+
+3 2
+1 2 4
+1 2 3