Package 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 java.lang.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
    Description
    Solution()
     

  • Method Summary

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

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • minPushBox

      public int minPushBox(char[][] grid)