Class Solution
Hard
Given an m x n
grid. Each cell of the grid has a sign pointing to the next cell you should visit if you are currently in this cell. The sign of grid[i][j]
can be:
1
which means go to the cell to the right. (i.e go fromgrid[i][j]
togrid[i][j + 1]
)2
which means go to the cell to the left. (i.e go fromgrid[i][j]
togrid[i][j - 1]
)3
which means go to the lower cell. (i.e go fromgrid[i][j]
togrid[i + 1][j]
)4
which means go to the upper cell. (i.e go fromgrid[i][j]
togrid[i - 1][j]
)
Notice that there could be some signs on the cells of the grid that point outside the grid.
You will initially start at the upper left cell (0, 0)
. A valid path in the grid is a path that starts from the upper left cell (0, 0)
and ends at the bottom-right cell (m - 1, n - 1)
following the signs on the grid. The valid path does not have to be the shortest.
You can modify the sign on a cell with cost = 1
. You can modify the sign on a cell one time only.
Return the minimum cost to make the grid have at least one valid path.
Example 1:
Input: grid = [[1,1,1,1],[2,2,2,2],[1,1,1,1],[2,2,2,2]]
Output: 3
Explanation: You will start at point (0, 0). The path to (3, 3) is as follows. (0, 0) –> (0, 1) –> (0, 2) –> (0, 3) change the arrow to down with cost = 1 –> (1, 3) –> (1, 2) –> (1, 1) –> (1, 0) change the arrow to down with cost = 1 –> (2, 0) –> (2, 1) –> (2, 2) –> (2, 3) change the arrow to down with cost = 1 –> (3, 3) The total cost = 3.
Example 2:
Input: grid = [[1,1,3],[3,2,2],[1,1,4]]
Output: 0
Explanation: You can follow the path from (0, 0) to (2, 2).
Example 3:
Input: grid = [[1,2],[4,3]]
Output: 1
Constraints:
m == grid.length
n == grid[i].length
1 <= m, n <= 100
1 <= grid[i][j] <= 4
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Constructor Summary
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Method Summary
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Constructor Details
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Solution
public Solution()
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Method Details
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minCost
public int minCost(int[][] grid)
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