23.08.12 Today’s Leetcode

63. Unique Paths II (medium)

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