Package g1201_1300.s1263_minimum_moves_to_move_a_box_to_their_target_location

Class Solution

  • public class Solution
extends Object
    1263 - Minimum Moves to Move a Box to Their Target Location.

    Hard

    A storekeeper is a game in which the player pushes boxes around in a warehouse trying to get them to target locations.

    The game is represented by an m x n grid of characters grid where each element is a wall, floor, or box.

    Your task is to move the box 'B' to the target position 'T' under the following rules:

    • The character 'S' represents the player. The player can move up, down, left, right in grid if it is a floor (empty cell).
    • The character '.' represents the floor which means a free cell to walk.
    • The character '#' represents the wall which means an obstacle (impossible to walk there).
    • There is only one box 'B' and one target cell 'T' in the grid.
    • The box can be moved to an adjacent free cell by standing next to the box and then moving in the direction of the box. This is a push.
    • The player cannot walk through the box.

    Return the minimum number of pushes to move the box to the target. If there is no way to reach the target, return -1.

    Example 1:

    Input:

     grid = [ ["#","#","#","#","#","#"],
         ["#","T","#","#","#","#"],
         ["#",".",".","B",".","#"],
         ["#",".","#","#",".","#"],
         ["#",".",".",".","S","#"],
         ["#","#","#","#","#","#"]]

    Output: 3

    Explanation: We return only the number of times the box is pushed.

    Example 2:

    Input:

     grid = [ ["#","#","#","#","#","#"],
         ["#","T","#","#","#","#"],
         ["#",".",".","B",".","#"],
         ["#","#","#","#",".","#"],
         ["#",".",".",".","S","#"],
         ["#","#","#","#","#","#"]]

    Output: -1

    Example 3:

    Input:

     grid = [ ["#","#","#","#","#","#"],
         ["#","T",".",".","#","#"],
         ["#",".","#","B",".","#"],
         ["#",".",".",".",".","#"],
         ["#",".",".",".","S","#"],
         ["#","#","#","#","#","#"]]

    Output: 5

    Explanation: push the box down, left, left, up and up.

    Constraints:

    • m == grid.length
    • n == grid[i].length
    • 1 <= m, n <= 20
    • grid contains only characters '.', '#', 'S', 'T', or 'B'.
    • There is only one character 'S', 'B', and 'T' in the grid.

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • minPushBox

        public int minPushBox​(char[][] grid)