[20250320] BOJ / G1 / 버스 갈아타기 / 권혁준

khj20006/202503/20 BOJ G1 버스 갈아타기.md

@@ -0,0 +1,148 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+class Bus{
+	int x1, y1, x2, y2;
+	Bus(int x1, int y1, int x2, int y2){
+		this.x1 = x1;
+		this.y1 = y1;
+		this.x2 = x2;
+		this.y2 = y2;
+	}
+
+	boolean intersect(Bus other) {
+
+		if(this.x1 == this.x2 && other.x1 == other.x2) {
+			if(this.x1 != other.x1) return false; 
+			if(this.y1 > other.y2 || this.y2 < other.y1) return false;
+			return true;
+		}
+
+		if(this.y1 == this.y2 && other.y1 == other.y2) {
+			if(this.y1 != other.y1) return false;
+			if(this.x1 > other.x2 || this.x2 < other.x1) return false;
+			return true;
+		}
+
+		if(this.x1 == this.x2) {
+			if(other.x1 <= this.x1 && this.x1 <= other.x2 && this.y1 <= other.y1 && other.y1 <= this.y2) {
+				return true;
+			}
+
+			return false;
+		}
+		if(other.y1 <= this.y1 && this.y1 <= other.y2 && this.x1 <= other.x1 && other.x1 <= this.x2) {
+			return true;
+		}
+
+		return false;
+	}
+}
+
+class Main {
+
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		if(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+
+	// Additional field
+
+	static int M, N, K, sx, sy, ex, ey;
+	static Bus[] bs;
+	static boolean[] starts, ends;
+
+	static boolean[][] V;
+
+	public static void main(String[] args) throws Exception {
+
+		ready();
+		solve();
+
+		bwEnd();
+
+	}
+
+	static void ready() throws Exception{
+
+		M = nextInt();
+		N = nextInt();
+		K = nextInt();
+		bs = new Bus[K];
+		V = new boolean[K][K];
+		for(int i=0;i<K;i++) {
+			int id = nextInt(), x1 = nextInt(), y1 = nextInt(), x2 = nextInt(), y2 = nextInt();
+			if(x1 == x2) {
+				int min = Math.min(y1, y2);
+				int max = Math.max(y1, y2);
+				y1 = min;
+				y2 = max;
+			}
+			else {
+				int min = Math.min(x1, x2);
+				int max = Math.max(x1, x2);
+				x1 = min;
+				x2 = max;
+			}
+			bs[i] = new Bus(x1,y1,x2,y2);
+		}
+		sx = nextInt();
+		sy = nextInt();
+		ex = nextInt();
+		ey = nextInt();
+		starts = new boolean[K];
+		ends = new boolean[K];
+
+	}
+
+	static void solve() throws Exception{
+
+		for(int i=0;i<K;i++) {
+			for(int j=i+1;j<K;j++) {
+				if(bs[i].intersect(bs[j])) {
+					V[i][j] = true;
+					V[j][i] = true;
+				}
+			}
+		}
+
+		for(int i=0;i<K;i++) {
+			if(bs[i].intersect(new Bus(sx,sy,sx,sy))) starts[i] = true;
+			if(bs[i].intersect(new Bus(ex,ey,ex,ey))) ends[i] = true;
+		}
+
+		Queue<int[]> Q = new LinkedList<>();
+		boolean[] vis = new boolean[K];
+		for(int i=0;i<K;i++) if(starts[i]) {
+			vis[i] = true;
+			Q.offer(new int[] {i,1});
+		}
+		while(!Q.isEmpty()) {
+			int[] now = Q.poll();
+			int n = now[0], t = now[1];
+			if(ends[n]) {
+				bw.write(t + "\n");
+				return;
+			}
+			for(int i=0;i<K;i++) if(i!=n && V[n][i] && !vis[i]) {
+				vis[i] = true;
+				Q.offer(new int[] {i,t+1});
+			}
+		}
+	}
+
+}
+
+```