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 limit' 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.

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public class Solution {    public int uniquePaths(int m, int n) {        int[][] paths = new int[m][n];        for(int i = 0; i < m; ++i) {            for(int j = 0; j < n; ++j) {                if(i == 0 && j == 0) {                    paths[0][0] = 1;                } else {                    paths[i][j] = (i==0 ? 0: paths[i - 1][j]) + (j ==0 ? 0: paths[i][j - 1]);                }            }        }        return paths[m - 1][n - 1];    }}

public class Solution {    public int uniquePathsWithObstacles(int[][] obstacleGrid) {        int m = obstacleGrid.length;        int n = obstacleGrid[0].length;        if(obstacleGrid[0][0] == 1 || obstacleGrid[m - 1][n - 1] == 1) {            return 0;        }        int[][] dp = new int[m][n];        dp[0][0] = 1;        for(int i = 1; i < n; ++i) {            if(obstacleGrid[0][i] == 0) {                dp[0][i] = dp[0][i - 1];            } else {                dp[0][i] = 0;            }        }        for(int i = 1; i < m; ++i) {            if(obstacleGrid[i][0] == 0) {                dp[i][0] = dp[i-1][0];            } else {                dp[i][0] = 0;            }        }        for(int i = 1; i < m; ++i) {            for(int j = 1; j < n; ++j) {                if(obstacleGrid[i][j] == 0) {                    dp[i][j] = dp[i-1][j] + dp[i][j - 1];                } else {                    dp[i][j] = 0;                }            }        }                return dp[m - 1][n - 1];    }}