인프런 커뮤니티 질문&답변

import java.util.*;

public class Main {
	public int solution(int[][] board, int[] moves) {
		int answer = 0;
		Stack<Integer> stack = new Stack<Integer>();
		for(int pos : moves) {
			for(int i =0; i < board.length; i++) {
				if(board[i][pos-1] != 0) {
					int tmp = board[i][pos-1];
					board[i][pos-1] = 0;
					if(!stack.isEmpty() && tmp == stack.peek()) {
						answer += 2;
						stack.pop();
					} else {
						stack.push(tmp);
						break;
					}
				}
			}
		}

		return answer;

	}

	public static void main(String[] args) {
		Main M = new Main();
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[][] board = new int[n][n];
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				board[i][j] = sc.nextInt();
			}
		}
		int m = sc.nextInt();
		int[] moves = new int[m];
		for (int i = 0; i < m; i++)
			moves[i] = sc.nextInt();
		System.out.println(M.solution(board, moves));
	}
}