public int uniquePathsWithObstacles(int[][] obstacleGrid) {

if(obstacleGrid == null || obstacleGrid.length == 0) return 0;

int m = obstacleGrid.length;

int n = obstacleGrid[0].length;

int[][] dp = new int[m][n];

if(obstacleGrid[0][0] == 0) dp[0][0] = 1;

else dp[0][0] = 0;

for(int i = 1; i < m; i++){

if(obstacleGrid[i][0] == 1) break;

else dp[i][0] = dp[i-1][0];

}

for(int i = 1; i < n; i++){

if(obstacleGrid[0][i] == 1) break;

else dp[0][i] = dp[0][i-1];

}

for(int i = 1; i < m; i++){

for(int j = 1; j < n; j++){

if(obstacleGrid[i][j] == 1) dp[i][j] = 0;

else if(dp[i-1][j] == 0 && dp[i][j-1] == 0) dp[i][j] = 0;

else dp[i][j] = dp[i-1][j]+dp[i][j-1];

}

}

return dp[m-1][n-1];

}

}