Unique Paths in Grid
Function Name: countUniquePaths
Description
Write a function `countUniquePaths` that calculates the number of unique paths from the top-left corner to the bottom-right corner of a MxN grid. However, there are some 'obstacles' represented by a 1 placed in some cells. The function should take two parameters: `m` and `n` representing the dimensions of the grid, and `obstacles` a 2D array where `obstacles[i][j] == 1` means there's an obstacle on the (i, j) cell.
The robot can only move either down or right at any point in time. If it encounters an obstacle, it cannot move further in that direction. If it's at the edge of the grid, it can only move in the direction that doesn't take it out of bounds.
Requirements
- The function `countUniquePaths(m, n, obstacles)` should return an integer, the number of unique paths from top-left to bottom-right, excluding paths that encounter obstacles.
- Consider the upper-left corner as starting point (0, 0) and the lower-right corner as end point (m-1, n-1).
- If the starting cell or the ending cell has an obstacle, return 0.
- The grid will always at least be a 1x1 grid.
- The `obstacles` array will have the same dimensions as the grid (MxN), and only contain 0s and 1s, where 1 indicates an obstacle.
Examples
// Example 1:countUniquePaths(3, 3, [[0, 0, 0], [0, 1, 0], [0, 0, 0]]); // return 2// Example 2:countUniquePaths(1, 1, [[0]]); // return 1// Example 3:countUniquePaths(3, 3, [[1, 0, 0], [0, 1, 0], [0, 0, 0]]); // return 0
Links
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