g1201_1300.s1263_minimum_moves_to_move_a_box_to_their_target_location

Class Solution

java.lang.Object

g1201_1300.s1263_minimum_moves_to_move_a_box_to_their_target_location.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 Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
int	minPushBox(char[][] grid)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

minPushBox

public int minPushBox(char[][] grid)