[20251208] BOJ / G5 / Takistusrada / 한종욱

Ukj0ng/202512/08 BOJ G5 Takistusrada.md

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+```
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static final int[] dvx = {0, 0, 0, 1, -1};
+    private static final int[] dvy = {0, 1, -1, 0, 0};
+    private static final int OFFSET = 50;
+    private static final int MAX_COORD = 100;
+    private static final int MAX_V = 7;
+    private static final int V_OFFSET = 7;
+    private static int targetX, targetY;
+    private static int N;
+    private static boolean[][] isObstacle;
+    private static boolean[][][][] visited;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        int result = BFS();
+
+        bw.write(String.valueOf(result));
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        targetX = Integer.parseInt(st.nextToken());
+        targetY = Integer.parseInt(st.nextToken());
+        N = Integer.parseInt(st.nextToken());
+
+        isObstacle = new boolean[MAX_COORD + 1][MAX_COORD + 1];
+        visited = new boolean[MAX_COORD + 1][MAX_COORD + 1][16][16];
+
+        for (int i = 0; i < N; i++) {
+            st = new StringTokenizer(br.readLine());
+            int ox = Integer.parseInt(st.nextToken());
+            int oy = Integer.parseInt(st.nextToken());
+
+            if (!OOB(ox + OFFSET, oy + OFFSET)) {
+                isObstacle[ox + OFFSET][oy + OFFSET] = true;
+            }
+        }
+    }
+
+    private static int BFS() {
+        Queue<int[]> q = new ArrayDeque<>();
+
+        int startX = 0 + OFFSET;
+        int startY = 0 + OFFSET;
+        int startVx = 0 + V_OFFSET;
+        int startVy = 0 + V_OFFSET;
+
+        q.add(new int[] {startX, startY, startVx, startVy, 0});
+        visited[startX][startY][startVx][startVy] = true;
+
+        while (!q.isEmpty()) {
+            int[] cur = q.poll();
+            int cx = cur[0];
+            int cy = cur[1];
+            int cvx = cur[2];
+            int cvy = cur[3];
+            int time = cur[4];
+
+            if (cx - OFFSET == targetX && cy - OFFSET == targetY) {
+                return time;
+            }
+
+            int realVx = cvx - V_OFFSET;
+            int realVy = cvy - V_OFFSET;
+
+            for (int i = 0; i < 5; i++) {
+                int nRealVx = realVx + dvx[i];
+                int nRealVy = realVy + dvy[i];
+
+                if (Math.abs(nRealVx) > MAX_V || Math.abs(nRealVy) > MAX_V) continue;
+
+                int nx = cx + nRealVx;
+                int ny = cy + nRealVy;
+                int nvx = nRealVx + V_OFFSET;
+                int nvy = nRealVy + V_OFFSET;
+
+                if (OOB(nx, ny) || visited[nx][ny][nvx][nvy] || hasCollision(cx, cy, nx, ny)) continue;
+                visited[nx][ny][nvx][nvy] = true;
+                q.add(new int[] {nx, ny, nvx, nvy, time + 1});
+            }
+        }
+
+        return -1; 
+    }
+
+    private static boolean hasCollision(int x1, int y1, int x2, int y2) {
+        int dx = x2 - x1;
+        int dy = y2 - y1;
+
+        if (dx == 0 && dy == 0) {
+            return isObstacle[x2][y2];
+        }
+
+        int steps = gcd(Math.abs(dx), Math.abs(dy));
+
+        int stepX = dx / steps;
+        int stepY = dy / steps;
+
+        for (int i = 1; i <= steps; i++) {
+            int checkX = x1 + stepX * i;
+            int checkY = y1 + stepY * i;
+
+            if (isObstacle[checkX][checkY]) return true;
+        }
+
+        return false;
+    }
+
+    private static int gcd(int a, int b) {
+        while (b != 0) {
+            int r = a % b;
+            a = b;
+            b = r;
+        }
+        return a;
+    }
+
+    private static boolean OOB(int x, int y) {
+        return x < 0 || x > MAX_COORD || y < 0 || y > MAX_COORD;
+    }
+}
+```