UniquePath2FromLeetcode

UniquePath2.java

public class Solution {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        
        int m = obstacleGrid.length;
        int n = obstacleGrid[0].length;
        
        int matrix[][] = new int[m][n];
        
        for(int i = n - 1; i >= 0; i--){
            if(obstacleGrid[m - 1][i] == 1)
                break;
            matrix[m - 1][i] = 1; 
        }
        
        for(int i = m - 1; i >=0; i--){
            if(obstacleGrid[i][n-1] == 1)
                break;
            matrix[i][n-1] = 1;
        }
        
         for(int i = m - 2; i >= 0; i--){
            for(int j = n - 2; j >=0; j--){
                if(obstacleGrid[i][j] == 1)
                    matrix[i][j] = 0;
                else
                    matrix[i][j] = matrix[i+1][j] + matrix[i][j+1];
            }
        }
        
        return matrix[0][0];
    }
    
}