Merge pull request #107 from AlgorithmWithGod/Seol-JY

[20250213] BOJ / G5 / 색칠하기 / 설진영

Author: ShinHeeEul

Seol-JY/202502/13 BOJ G5 색칠하기.md

@@ -0,0 +1,77 @@
+```java
+
+import java.io.*;
+import java.util.*;
+public class Main {
+    private static final int EMPTY = 0;
+    private static final int RED = 1;
+    private static final int BLUE = -1;
+
+    static int N, M;
+    static int[][] arr;
+    static int[] palette;
+    static Queue<int[]> queue = new LinkedList<>();
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int T = Integer.parseInt(br.readLine());
+
+        for (int t = 0; t < T; t++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            N = nextInt(st);
+            M = nextInt(st);
+            arr = new int[N+1][N+1];
+            palette = new int[N+1];
+            
+            for (int i = 0; i < M; i++) {
+                st = new StringTokenizer(br.readLine());
+                int x = nextInt(st);
+                int y = nextInt(st);
+
+                arr[x][y] = 1;
+                arr[y][x] = 1;
+            }
+            boolean isImpossible = false;
+            for (int i = 1; i < N+1; i++) { 
+                if (palette[i] == EMPTY) {
+                    if (!bfs(i)) {
+                        System.out.println("impossible");
+                        isImpossible = true;
+                        break;
+                    }
+                }
+            }
+            if (!isImpossible) {
+                System.out.println("possible");
+            }
+        }
+    }
+
+    private static boolean bfs(int i) {
+        palette[i] = RED;
+        queue.add(new int[]{i, RED});
+        while (!queue.isEmpty()) {
+            int[] target = queue.poll();
+
+            for (int j = 1; j < N+1; j++) {
+                if(arr[target[0]][j] == 1) {
+                    if (palette[j] == target[1]) {
+                        queue.clear();
+                        return false;
+                    }
+                    if (palette[j] == EMPTY) {
+                        palette[j] = -target[1];
+                        queue.add(new int[]{j, -target[1]});
+                    }
+                }
+            }
+        }
+
+        return true;
+    }
+
+    private static int nextInt(StringTokenizer st) {
+        return Integer.parseInt(st.nextToken());
+    }
+}
+```