recursion-excercise.js

var execute = function () {

        var field = [
            [{a: 1}, {a: 2}, {a: 3}, {a: 4}],
            [{b: 1}, {b: 2}, {b: 3}, {b: 4}],
            [{c: 1}, {c: 2}, {c: 3}, {c: 4}],
            [{d: 1}, {d: 2}, {d: 3}, {d: 4}]
        ];

        var directions = {
            right: [0, 1],
            bottom: [1, 0],
            left: [0, -1],
            top: [-1, 0]
        };

        var directionsOrder = ['right', 'bottom', 'left', 'top'];

        var currentAddress = [0,0];
        var newAddress = [];

        var getNewAddress = function (currentAddress, directions, directionsOrder, currentDirection) {
            return [
                currentAddress[0] + directions[directionsOrder[currentDirection]][0],
                currentAddress[1] + directions[directionsOrder[currentDirection]][1]
            ];
        };

        var visitCell = function (field, currentAddress, currentDirection) {
            // Print address
            console.log(field[currentAddress[0]][currentAddress[1]]);

            // mark cell as visited
            field[currentAddress[0]][currentAddress[1]] = 'VISITED';

            newAddress = getNewAddress(currentAddress, directions, directionsOrder, currentDirection);

            // Check if newAddress does not exist, we change direction based on the direction order.
            if (typeof field[newAddress[0]] == 'undefined'
                || typeof field[newAddress[0]][newAddress[1]] == 'undefined'
            ) {
                currentDirection = (currentDirection === 3) ? 0 : currentDirection + 1;
                newAddress = getNewAddress(currentAddress, directions, directionsOrder, currentDirection);
                visitCell(field, newAddress, currentDirection);
                return;
            }

            if (field[newAddress[0]][newAddress[1]] == 'VISITED') {
                // If VISITED we change direction
                currentDirection = (currentDirection === 3) ? 0 : currentDirection + 1;
                newAddress = getNewAddress(currentAddress, directions, directionsOrder, currentDirection);
                // if new direction is visited we return, there is no unvisited cells;
                if (field[newAddress[0]][newAddress[1]] == 'VISITED') {
                    return;
                } else {
                    visitCell(field, newAddress, currentDirection);
                }
            } else {
                visitCell(field, newAddress, currentDirection)
            }
        };

        visitCell(field, currentAddress, 0);
    }