Imagine a robot sitting on the upper left corner of grid with r rows and c columns. The robot can only move in two directions, right and down, but certain cells are "off limits" such that the robot cannot step on them. Design an algorithm to find a path for the robot from the top left to the bottom right.
"off limits" and empty grid are represented by 1 and 0 respectively.
Return a valid path, consisting of row number and column number of grids in the path.
Example 1:
Input: [ [0,0,0], [0,1,0], [0,0,0] ] Output: [[0,0],[0,1],[0,2],[1,2],[2,2]]
Note:
r, c <= 100