[20250803] BOJ / G4 / 여행 가자 / 이종환

Author: 0224LJH

0224LJH/202508/3 BOJ 여행 가자.md

@@ -0,0 +1,95 @@
+```java
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+
+public class Main {
+
+
+    static StringBuilder sb = new StringBuilder();
+    static int cityCnt,planCityCnt;
+    static int[][] arr;
+    static int[] plan,parent;
+
+
+    public static void main(String[] args) throws IOException {
+        init();
+        process();
+        print();
+    }
+
+    private static void init() throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        cityCnt = Integer.parseInt(br.readLine());
+        planCityCnt = Integer.parseInt(br.readLine());
+        arr = new int[cityCnt][cityCnt];
+        parent = new int[cityCnt];
+        for (int i = 0; i < cityCnt; i++) {
+            parent[i] = i;
+        }
+        plan = new int[planCityCnt];
+
+        for (int i = 0; i < cityCnt; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < cityCnt; j++) {
+                arr[i][j] = Integer.parseInt(st.nextToken());
+            }
+        }
+
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < planCityCnt; i++) {
+            plan[i] = Integer.parseInt(st.nextToken())-1;
+        }
+
+    }
+
+    private static void process() throws IOException {
+        for (int i = 0; i < cityCnt; i++) {
+            for (int j = 0; j < cityCnt; j++) {
+                if (arr[i][j] == 1) union(i,j);
+            }
+        }
+
+        for (int i = 1; i < planCityCnt; i++) {
+            int preRoot = find(plan[i-1]);
+            int curRoot = find(plan[i]);
+            if (preRoot != curRoot) {
+                System.out.println("NO");
+                return;
+            }
+        }
+
+        System.out.println("YES");
+
+    }
+
+    private static void union(int a, int b) {
+        int aRoot = find(a);
+        int bRoot = find(b);
+
+        if (aRoot == bRoot) return;
+
+        if (aRoot > bRoot) {
+            parent[bRoot] = aRoot;
+        } else {
+            parent[aRoot] = bRoot;
+        }
+
+    }
+
+    private static int find(int x) {
+        if (x == parent[x]) return x;
+
+        return parent[x] = find(parent[x]);
+    }
+
+
+
+    private static void print() {
+        System.out.print(sb.toString());
+    }
+}
+```