Merge pull request #66 from AlgorithmWithGod/khj20006

[20250210] BOJ / 플래3 / Game on Tree / 권혁준

Author: ShinHeeEul

khj20006/202502/10 BOJ P3 Game on Tree.md

@@ -0,0 +1,79 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+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;
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static int nextInt() {return Integer.parseInt(st.nextToken());}
+	static long nextLong() {return Long.parseLong(st.nextToken());}
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+
+	static int[] d;
+	static List<Integer>[] V;
+	static int N, ans = -1;
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+	
+		bwEnd();
+	}
+	
+	static void ready() throws Exception{
+		
+		N = Integer.parseInt(br.readLine());
+		d = new int[N+1];
+		V = new ArrayList[N+1];
+		for(int i=1;i<=N;i++) V[i] = new ArrayList<>();
+		nextLine();
+		for(int i=2;i<=N;i++) {
+			int p = nextInt();
+			V[p].add(i);
+		}
+		
+	}
+	
+	static void solve() throws Exception{
+		
+		dfs(1);
+		if(d[1] <= 1) {
+			bw.write("FIRST\n");
+			bw.write(findAns(1) + "\n");
+		}
+		else bw.write("SECOND");
+		
+	}
+	
+	static void dfs(int n) {
+		if(V[n].isEmpty()) d[n] = 2;
+		for(int i:V[n]) {
+			dfs(i);
+			d[n] += Math.max(0, d[i]-1);
+		}
+	}
+	
+	static int findAns(int n) {
+		if(V[n].isEmpty()) return n;
+		int next = n, max = -1;
+		for(int i:V[n]) {
+			if(d[i] > max) {
+				max = d[i];
+				next = i;
+			}
+		}
+		return findAns(next);
+	}
+	
+}
+
+```