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Problem: Unique Paths III

Statement

You are given a  m×nm \times n  integer array, grid, where each cell, grid[i][j], can have one of the following values:

  • 1 indicates the starting point. There is exactly one such square.

  • 2 marks the ending point. There is exactly one such square.

  • 0 represents empty squares that can be walked over.

  • -1 represents obstacles that cannot be crossed.

Your task is to return the total number of unique four-directional paths from the starting square (1) to the ending square (2), such that every empty square is visited exactly once during the walk.

Constraints:

  • mm ==== grid.length

  • nn ==== grid[i].length

  • 1≤1 \leqm,nm, n ≤20\leq 20

  • 1≤1 \leq m×nm \times n ≤20\leq 20

  • −1≤-1 \leq grid[i][j] ≤2\leq 2

  • There is exactly one starting cell and one ending cell.

Problem
Submissions
Debug

Problem: Unique Paths III

Statement

You are given a  m×nm \times n  integer array, grid, where each cell, grid[i][j], can have one of the following values:

  • 1 indicates the starting point. There is exactly one such square.

  • 2 marks the ending point. There is exactly one such square.

  • 0 represents empty squares that can be walked over.

  • -1 represents obstacles that cannot be crossed.

Your task is to return the total number of unique four-directional paths from the starting square (1) to the ending square (2), such that every empty square is visited exactly once during the walk.

Constraints:

  • mm ==== grid.length

  • nn ==== grid[i].length

  • 1≤1 \leqm,nm, n ≤20\leq 20

  • 1≤1 \leq m×nm \times n ≤20\leq 20

  • −1≤-1 \leq grid[i][j] ≤2\leq 2

  • There is exactly one starting cell and one ending cell.