230608 프렌즈4블록

public int solution(int m, int n, String[] board) {
    int answer = 0;
    char[][] copy = new char[m][n]; 

    for (int i = 0; i < m; i++) {
        copy[i] = board[i].toCharArray();
    }

    boolean flag = true;

    while (flag) {
        boolean[][] v = new boolean[m][n]; 
        flag = false;

        for (int i = 0; i < m - 1; i++) {
            for (int j = 0; j < n - 1; j++) {
                if (copy[i][j] == '-') {
                    continue; 
                }

                if (check(i, j, copy)) {
                    v[i][j] = true;
                    v[i][j + 1] = true;
                    v[i + 1][j] = true;
                    v[i + 1][j + 1] = true;
                    flag = true;
                }
            }
        }

        answer += erase(m, n, copy, v);
    }

    return answer;
}

public boolean check(int x, int y, char[][] board) {
    char ch = board[x][y];
    return ch == board[x][y + 1] && ch == board[x + 1][y] && ch == board[x + 1][y + 1];
}

public int erase(int m, int n, char[][] board, boolean[][] v) {
    int cnt = 0;

    mark(m, n, board, v);

    for (int i = 0; i < n; i++) {
        Queue<Character> q = new LinkedList<>();

        for (int j = m - 1; j >= 0; j--) {
            if (board[j][i] == '.') {
                cnt++; 
            } else {
                q.add(board[j][i]);
            }
        }

        int idx = m - 1;

        while (!q.isEmpty()) {
            board[idx--][i] = q.poll();
        }

        for (int j = idx; j >= 0; j--) {
            board[j][i] = '-';
        }
    }

    return cnt;
}

private void mark(int m, int n, char[][] board, boolean[][] v) {
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (v[i][j]) {
                board[i][j] = '.';
            }
        }
    }
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/17679