You are given an m * n grid representing a field, where each cell can either be a 0 or a 1. A 0 represents an empty cell, while a 1 represents a cell that is blocked and cannot be passed through. Assume that there is a robot located at the top-right corner of the grid (i.e., grid[0][n-1]), and the robot needs to reach the bottom-left corner of the grid (i.e., grid[m-1][0]). The robot can only move left or down at any point in time. Write a function that takes the grid as input and returns the number of unique paths the robot can take to reach the bottom-left corner, without passing through any blocked cells. Explain your approach. What is the time complexity? Example: (m=4, n = 6) 0 0 0 Destination 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Robot 0 0 0