LeetCode Unique Paths II

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
        vector<vector<int> >& dp = obstacleGrid;
        if (dp.empty() || dp[0].empty()) return 0;
        dp[0][0] = (dp[0][0] == 1) ? 0 : 1;
        for (int i=1; i<dp.size(); i++) {
            dp[i][0] = (dp[i][0] == 1) ? 0 : dp[i-1][0];
        }
        for (int i=1; i<dp[0].size(); i++) {
            dp[0][i] = (dp[0][i] == 1) ? 0 : dp[0][i-1];
        }
        for (int i=1; i<dp.size(); i++) {
            for (int j=1; j<dp[i].size(); j++) {
                dp[i][j] = (dp[i][j] == 1) ? 0 : dp[i-1][j] + dp[i][j-1];
            }
        }
        return dp.back().back();
    }
};