algorithm_4block

function turn(m, n, board, answer) {
    var removeItem = [];
    for (var i = 1; i < m; i++) {
        for (var j = 1; j < n; j++) {
            var item = board[i][j];
            if (item === '0') continue;
            var topLeft = board[i - 1][j - 1];
            var top = board[i - 1][j];
            var left = board[i][j - 1];
            
            if (item === topLeft && item === top && item === left) {
                removeItem.push((i - 1) + ',' + (j - 1));
                removeItem.push((i - 1) + ',' + j);
                removeItem.push(i + ',' + (j - 1));
                removeItem.push(i + ',' + j);
            }
        }
    }
    
    removeItem = removeItem.reduce((acc, cur) => {
        if (acc.indexOf(cur) < 0) {
            acc.push(cur);
        }
        return acc;
    }, []);
    if (removeItem.length > 0) {
        answer += removeItem.length;
        removeItem.forEach(i => {
            var y = parseInt(i.split(',')[0], 10);
            var x = parseInt(i.split(',')[1], 10);
            
            board[y][x] = '0';
        });
        for (var i = 1; i < m; i++) {
            for (var j = 0; j < n; j++) {
                var flag = true;
                var sY = i;
                var sX = j;
                while(sY > 0) {
                    if (board[sY][sX] === '0') {
                        board[sY][sX] = board[sY - 1][sX];
                        board[sY - 1][sX] = '0';
                    }
                    sY--;
                }
            }
        }
        answer = turn(m, n, board, answer);
    }
    return answer;
}

function solution(m, n, board) {
    var answer = 0;
    board = board.map(row => row.split(''));
    answer = turn(m, n, board, answer);
    return answer;
}