[BFS] baekjoon-13549

Author: Seogeurim

README.md

@@ -43,6 +43,7 @@
 | 08  |     | [Baekjoon-7576 토마토](./src/BFS/P7576) |      |
 | 09  |     | [Baekjoon-1697 숨바꼭질](./src/BFS/P1697) |      |
 | 10  |     | [Baekjoon-14226 이모티콘](./src/BFS/P14226) |      |
+| 11  |     | [Baekjoon-13549 숨바꼭질 3](./src/BFS/P13549) |      |
 
 ## Simulation
 

src/BFS/P13549/Main.java

@@ -0,0 +1,77 @@
+package BFS.P13549;
+
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int N, K;
+    static Queue<Position> q = new LinkedList<>();
+    static boolean[] visited = new boolean[100001];
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        K = Integer.parseInt(st.nextToken());
+
+        int ans = Integer.MAX_VALUE;
+        boolean flag = false;
+        q.offer(new Position(N, 0));
+        while (!q.isEmpty()) {
+            Position cur = q.poll();
+            visited[cur.pos] = true;
+
+            if (cur.pos == K) {
+                ans = Math.min(ans, cur.time);
+                flag = true;
+            }
+
+            if (cur.pos - 1 == K) {
+                ans = Math.min(ans, cur.time + 1);
+                flag = true;
+            } else if (!flag && isValidPath(cur.pos - 1) && !visited[cur.pos - 1]) {
+                q.offer(new Position(cur.pos - 1, cur.time + 1));
+            }
+
+            if (cur.pos + 1 == K) {
+                ans = Math.min(ans, cur.time + 1);
+                flag = true;
+            } else if (!flag && isValidPath(cur.pos + 1) && !visited[cur.pos + 1]) {
+                q.offer(new Position(cur.pos + 1, cur.time + 1));
+            }
+
+            if (cur.pos * 2 == K) {
+                ans = Math.min(ans, cur.time);
+                flag = true;
+            } else if (!flag && isValidPath(cur.pos * 2) && !visited[cur.pos * 2]) {
+                q.offer(new Position(cur.pos * 2, cur.time));
+            }
+        }
+
+        System.out.println(ans);
+    }
+
+    static boolean isValidPath(int pos) {
+        return 0 <= pos && pos <= 100000;
+    }
+}
+
+class Position {
+    int pos;
+    int time;
+
+    public Position(int pos, int time) {
+        this.pos = pos;
+        this.time = time;
+    }
+
+    @Override
+    public String toString() {
+        return "Position{" +
+                "pos=" + pos +
+                ", time=" + time +
+                '}';
+    }
+}

src/BFS/P13549/README.md

@@ -0,0 +1,5 @@
+## [baekjoon-13549] 숨바꼭질 3
+
+![image](https://user-images.githubusercontent.com/22045163/101243817-1127ee00-3746-11eb-8834-9f0d8f536ec0.png)
+
+BFS 문제임을 판단한 후, `정확하게 조건 파악하기` & `메모리 초과 신경 쓰기` 로 문제를 풀어나가면 되겠다.