Unique Paths II

Follow up for "Unique Paths":

Now consider if some obstacles are added to the grids. How many unique paths would there be?

An obstacle and empty space is marked as 1 and 0 respectively in the grid.

Notice

m and n will be at most 100.

Example

For example,

There is one obstacle in the middle of a 3x3 grid as illustrated below.

[
  [0,0,0],
  [0,1,0],
  [0,0,0]
]

Solution

class Solution:
    """
    @param obstacleGrid: An list of lists of integers
    @return: An integer
    """
    def uniquePathsWithObstacles(self, obstacleGrid):
        # write your code here
        if obstacleGrid[0][0] == 1:
            return 0
        m, n = len(obstacleGrid), len(obstacleGrid[0])
        F = [[0 for x in range(n)] for y in range(m)]
        F[0][0] = 1

        for row in range(1,m):
            if obstacleGrid[row][0] != 1:
                F[row][0] = 1
            else:
                break

        for col in range(1,n):
            if obstacleGrid[0][col] != 1:
                F[0][col] = 1
            else:
                break

        for row in range(1,m):
            for col in range(1,n):
                if obstacleGrid[row][col] != 1:
                    F[row][col] = F[row - 1][col] + F[row][col - 1]
                else:
                    F[row][col] = 0

        return F[-1][-1]