[SW Expert Academy, SWEA 1231] [S/W 문제해결 기본] 9일차 - 중위순회 (java)

https://swexpertacademy.com/main/code/problem/problemDetail.do?contestProbId=AV140YnqAIECFAYD&categoryId=AV140YnqAIECFAYD&categoryType=CODE&problemTitle=1231&orderBy=FIRST_REG_DATETIME&selectCodeLang=ALL&select-1=&pageSize=10&pageIndex=1

SW Expert Academy

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※ SW Expert 아카데미의 문제를 무단 복제하는 것을 금지합니다.

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import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Solution {
	
	static int N;
	static char[] key;
	static int[][] child;
	static StringBuilder result;
	
	private static void inOrder(int node) {
		// left child가 있으면 재귀
		if(child[node][0] != 0) inOrder(child[node][0]);
		
		// 자신 추가
		result.append(key[node]);
		
		// right child가 있으면 재귀
		if(child[node][1] != 0) inOrder(child[node][1]);
	}

	public static void main(String[] args) throws Exception{

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st;
		result = new StringBuilder();
		
		for (int tc = 1; tc <= 10; tc++) {
			result.append("#" + tc + " ");
			
			N = Integer.parseInt(br.readLine());
			
			key = new char[N + 1];
			child = new int[N + 1][2];
			for (int i = 0; i < N; i++) {
				st = new StringTokenizer(br.readLine());
				int node = Integer.parseInt(st.nextToken());
				key[node] = st.nextToken().toCharArray()[0];
				if(st.hasMoreTokens()) child[node][0] = Integer.parseInt(st.nextToken());
				if(st.hasMoreTokens()) child[node][1] = Integer.parseInt(st.nextToken());
			}
			
			// in-order 순회
			inOrder(1);
			result.append("\n");
		}
		
		// 출력
		System.out.println(result);
	}

}