[백준 19236] 청소년 상어 - 시뮬레이션

Author: HiiWee

hoseok/week35/Boj19236.java

@@ -0,0 +1,150 @@
+import java.io.*;
+import java.util.*;
+
+class Main {
+
+    static class Fish {
+        int r, c, dir;
+        boolean isAlive;
+
+        Fish(int r, int c, int dir, boolean isAlive) {
+            this.r = r;
+            this.c = c;
+            this.dir = dir;
+            this.isAlive = isAlive;
+        }
+    }
+
+    static class Shark {
+        int r, c, dir, sum;
+
+        Shark(int r, int c, int dir, int sum) {
+            this.r = r;
+            this.c = c;
+            this.dir = dir;
+            this.sum = sum;
+        }
+    }
+
+    private static final int[] rows = {-1, -1, 0, 1, 1, 1, 0, -1};
+    private static final int[] cols = {0, -1, -1, -1, 0, 1, 1, 1};
+    private static int max;
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        int[][] map = new int[4][4];
+        Fish[] fishes = new Fish[17];
+
+        for (int i = 0; i < 4; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < 4; j++) {
+                int fishNumber = Integer.parseInt(st.nextToken());
+                int dir = Integer.parseInt(st.nextToken());
+                map[i][j] = fishNumber;
+                fishes[fishNumber] = new Fish(i, j, dir - 1, true);
+            }
+        }
+
+        int fishNumber = map[0][0];
+        map[0][0] = 0;
+        fishes[fishNumber].isAlive = false;
+        startMove(map, fishes, new Shark(0, 0, fishes[fishNumber].dir, fishNumber));
+
+        bw.write(max + "");
+        bw.flush();
+        bw.close();
+    }
+
+    public static void startMove(int[][] map, Fish[] fishes, Shark shark) {
+        int[][] copyMap = copyMap(map);
+        Fish[] copyFishes = copyFishes(fishes);
+        max = Math.max(max, shark.sum);
+
+        moveFish(copyMap, copyFishes, shark);
+
+        for (int i = 1; i < 4; i++) {
+            int nextR = shark.r + rows[shark.dir] * i;
+            int nextC = shark.c + cols[shark.dir] * i;
+
+            if (nextR < 0 || nextC < 0 || nextR >= 4 || nextC >= 4) {
+                break;
+            }
+            if (copyMap[nextR][nextC] != 0) {
+                int fishNumber = copyMap[nextR][nextC];
+                copyMap[nextR][nextC] = 0;
+                copyFishes[fishNumber].isAlive = false;
+                startMove(copyMap, copyFishes, new Shark(nextR, nextC, copyFishes[fishNumber].dir, shark.sum + fishNumber));
+
+                copyMap[nextR][nextC] = fishNumber;
+                copyFishes[fishNumber].isAlive = true;
+            }
+        }
+    }
+
+    public static void moveFish(int[][] map, Fish[] fishes, Shark shark) {
+        for (int i = 1; i <= 16; i++) {
+            Fish fish = fishes[i];
+
+            // 이미 죽은 물고기나, 상어의 위치라면 불가능
+            if (!fish.isAlive || fish.r == shark.r && fish.c == shark.c) {
+                continue;
+            }
+            for (int j = 0; j < 8; j++) {
+                int nextDir = (fish.dir + j) % 8;
+                int nextR = fish.r + rows[nextDir];
+                int nextC = fish.c + cols[nextDir];
+
+                if (nextR < 0 || nextR >= 4 || nextC < 0 || nextC >= 4) {
+                    continue;
+                }
+                if (nextR == shark.r && nextC == shark.c) {
+                    continue;
+                }
+                // 빈칸이라면
+                fish.dir = nextDir;
+                if (map[nextR][nextC] == 0) {
+                    map[nextR][nextC] = map[fish.r][fish.c];
+                    map[fish.r][fish.c] = 0;
+                    fish.r = nextR;
+                    fish.c = nextC;
+                } else {
+                    // 물고기 자리 스왑
+                    Fish swapFish = fishes[map[nextR][nextC]];
+                    swapFish(fish, swapFish);
+                    int tempNumber = map[fish.r][fish.c];
+                    map[fish.r][fish.c] = map[swapFish.r][swapFish.c];
+                    map[swapFish.r][swapFish.c] = tempNumber;
+                }
+                break;
+            }
+        }
+    }
+
+    public static void swapFish(Fish from, Fish to) {
+        int tempR = from.r;
+        int tempC = from.c;
+        from.r = to.r;
+        from.c = to.c;
+        to.r = tempR;
+        to.c = tempC;
+    }
+
+    public static Fish[] copyFishes(Fish[] fishes) {
+        Fish[] copyFishes = new Fish[17];
+        for (int i = 1; i <= 16; i++) {
+            copyFishes[i] = new Fish(fishes[i].r, fishes[i].c, fishes[i].dir, fishes[i].isAlive);
+        }
+        return copyFishes;
+    }
+
+    public static int[][] copyMap(int[][] map) {
+        int[][] copyMap = new int[4][4];
+        for (int i = 0; i < 4; i++) {
+            for (int j = 0; j < 4; j++) {
+                copyMap[i][j] = map[i][j];
+            }
+        }
+        return copyMap;
+    }
+}