[유병규-13주차 알고리즘 스터디]

유병규_13주차/[BOJ-23290] 마법사 상어와 복제.java

@@ -0,0 +1,172 @@
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    private static int[][] fd = {{0,-1},{-1,-1},{-1,0},{-1,1},{0,1},{1,1},{1,0},{1,-1}};
+    private static int[][] sd = {{-1,0},{0,-1},{1,0},{0,1}};
+    private static int max;
+    private static int[][] map;
+    private static Node[] path;
+
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int n = 4;
+
+        map = new int[n][n];
+        int[][] smallMap = new int[n][n];
+
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        int m = Integer.parseInt(st.nextToken());
+        int s = Integer.parseInt(st.nextToken());
+
+        Set<Fish> fishes = new HashSet<>();
+        for(int i=0; i<m; i++) {
+            st = new StringTokenizer(br.readLine());
+            int x = Integer.parseInt(st.nextToken())-1;
+            int y = Integer.parseInt(st.nextToken())-1;
+            int dir = Integer.parseInt(st.nextToken())-1;
+
+            fishes.add(new Fish(x, y, dir));
+            map[x][y]++;
+        }
+
+        st = new StringTokenizer(br.readLine());
+        int x = Integer.parseInt(st.nextToken())-1;
+        int y = Integer.parseInt(st.nextToken())-1;
+        int[] shark = {x, y};
+
+        //풀이 시작
+        int time = 0;
+        while(time < s) {
+            //물고기 냄새 시간 증가
+            for(int i=0; i<4; i++) {
+                for(int j=0; j<4; j++) {
+                    if(smallMap[i][j] > 0) smallMap[i][j]++;
+                }
+            }
+
+            //기존 물고기 저장
+            Queue<Fish> q = new LinkedList<>();
+
+            //물고기 이동
+            for(Fish fish : fishes) {
+                q.add(new Fish(fish.x, fish.y, fish.dir));
+
+                for(int i=0; i<fd.length; i++) {
+                    int idx = (fish.dir-i) < 0 ? fish.dir-i+8 : fish.dir-i;
+                    int nx = fish.x + fd[idx][0];
+                    int ny = fish.y + fd[idx][1];
+
+                    if(nx<0 || nx>=n || ny<0 || ny>=4 || smallMap[nx][ny] > 0) continue;
+                    if(nx==shark[0] && ny==shark[1]) continue;
+
+                    map[fish.x][fish.y]--;
+                    map[nx][ny]++;
+                    fish.x = nx;
+                    fish.y = ny;
+                    fish.dir = idx;
+                    break;
+                }
+
+            }
+
+            //상어 이동
+            max = -1;
+            path = new Node[3];
+            dfs(0, shark[0], shark[1], 0, new Node(shark[0], shark[1], null));
+            List<Fish> remove = new ArrayList<>();
+            for(int i=0; i<3; i++) {
+                Node node = path[i];
+                if(map[node.x][node.y] == 0) continue;
+                map[node.x][node.y] = 0;
+                for(Fish fish : fishes) {
+                    if(fish.x == node.x && fish.y == node.y) remove.add(fish);
+                }
+                smallMap[node.x][node.y] = 1;
+            }
+            fishes.removeAll(remove);
+            shark[0] = path[2].x;
+            shark[1] = path[2].y;
+
+            //물고기 냄새 제거
+            for(int i=0; i<n; i++) {
+                for(int j=0; j<n; j++) {
+                    if(smallMap[i][j] > 2) smallMap[i][j] = 0;
+                }
+            }
+
+            //물고기 복사
+            while(!q.isEmpty()) {
+                Fish fish = q.poll();
+                fishes.add(fish);
+                map[fish.x][fish.y]++;
+            }
+
+            time++;
+        }
+
+        int count = 0;
+        for(int i=0; i<n; i++) {
+            for(int j=0; j<n; j++) {
+                count += map[i][j];
+            }
+        }
+
+        System.out.println(count);
+    }
+
+    private static void dfs(int dept, int x, int y, int count, Node node) {
+        if(dept == 3) {
+            if(count <= max) return;
+            max = count;
+            Node current = node;
+            for(int i=2; i>=0; i--) {
+                path[i] = current;
+                current = current.pre;
+            }
+            return;
+        }
+
+        for(int i=0; i<sd.length; i++) {
+            int nx = x + sd[i][0];
+            int ny = y + sd[i][1];
+
+            if(nx<0 || nx>=4 || ny<0 || ny>=4) continue;
+            int nCount = count+map[nx][ny];
+            Node temp = node;
+            while(temp.pre != null) {
+                if(temp.x == nx && temp.y == ny) {
+                    nCount = count;
+                    break;
+                }
+                temp = temp.pre;
+            }
+            dfs(dept+1, nx, ny, nCount, new Node(nx, ny, node));
+        }
+    }
+
+    private static class Fish{
+        int x;
+        int y;
+        int dir;
+
+        public Fish(int x, int y, int dir) {
+            this.x = x;
+            this.y = y;
+            this.dir = dir;
+        }
+    }
+
+    private static class Node{
+        int x;
+        int y;
+        Node pre;
+
+        public Node(int x, int y, Node pre) {
+            this.x = x;
+            this.y = y;
+            this.pre = pre;
+        }
+    }
+}