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.

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]
]

The total number of unique paths is 2.

Note: m and n will be at most 100.

Solution:
basic 2-d dynamic programming + conditions check

public class Solution {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        int rowNum = obstacleGrid.length;
        int colNum = obstacleGrid[0].length;
        if((rowNum == 0 && colNum == 0) || (obstacleGrid[0][0] == 1)) return 0;
        int[][] result = new int[rowNum][colNum];
        for(int i = 0; i < rowNum; i++){
            for(int j = 0; j < colNum; j++){
                if(obstacleGrid[i][j] == 1) {result[i][j]=0;continue;}
                if(i == 0 && j == 0) result[i][j] = 1;
                else if(i == 0){
                    result[i][j] = obstacleGrid[i][j-1] == 0 ? result[i][j-1] : 0;
                }
                else if(j == 0){
                    result[i][j] = obstacleGrid[i-1][j] == 0 ? result[i-1][j] : 0;
                }
                else{
                    result[i][j] = 0;
                    result[i][j] +=  obstacleGrid[i][j-1] == 0 ? result[i][j-1] : 0;
                    result[i][j] +=  obstacleGrid[i-1][j] == 0 ? result[i-1][j] : 0; 
                }
            }
        }
        return result[rowNum-1][colNum-1];
    }
}