NCorreia100 / shortestPath

Algorithm that retrieves distance to target within a 2D array

Shortest Path

Given a 2-D array as input containing 0s (open area) and 1s (obstacle), find target marked with 9 and return number of moves.

Can only move horizontally or vertically. Start at [0,0] coordinate, but if it's not available go to the next coordinate to the right, then down. If there's no solution return -1.

   var inputEx=  [
        [0,1,1,0],
        [0,0,1,0],
        [1,0,9,0],
        [1,0,0,0]
    ];

  shortestPath(inputEx); ~~~> 3

Solution Approach:

Used a linked-list containing a queue (FIFO) of nodes. A 2D array initialized to its 0 value was also used to keep track of which coordinates were already checked to prevent circling back.

An alternative approach would be to use a Graph with search-in-breadth. Implementing Dijkstra's algorithm approach led to a smaller time complexity of O(n) (linear) as each coordinate is checked only once (or never).