/*
 * @lc app=leetcode id=63 lang=cpp
 *
 * [63] Unique Paths II
 * T(n) = O(m * n)
 * S(n) = O(m * n)
 */
class Solution
{
public:
    int uniquePathsWithObstacles(vector<vector<int>> &obstacleGrid)
    {
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        vector<vector<long>> dp(m + 1, vector<long>(n + 1, 0));
        dp[0][1] = 1;

        for (int i = 1; i <= m; i++)
        {
            for (int j = 1; j <= n; j++)
            {
                if (!obstacleGrid[i - 1][j - 1])
                    dp[i][j] = dp[i][j - 1] + dp[i - 1][j];
            }
        }
        return dp[m][n];
    }
};