Day 34 — Unique Paths II

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