[LeetCode] Unique Paths II

class Solution {public:    int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {        int m = obstacleGrid.size(),n = obstacleGrid[0].size();        vector<vector<int> > res(m, vector<int>(n));        res[0][0] = obstacleGrid[0][0] == 0 ? 1 : 0;        for(int i = 1;i < n;i ++)            res[0][i] = obstacleGrid[0][i] == 0 ? res[0][i - 1] : 0;        for(int i = 1;i < m;i ++)            res[i][0] = obstacleGrid[i][0] == 0 ? res[i - 1][0] : 0;        for(int i = 1;i < m;i ++)            for(int j = 1;j < n;j ++)                res[i][j] = obstacleGrid[i][j] == 0 ? res[i - 1][j] + res[i][j - 1] : 0;        return res[m - 1][n - 1];    }};