Follow up for "Unique Paths": Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as 1 and 0 respectively in the grid. For example, There is one obstacle in the middle of a 3x3 grid as illustrated below. [ [0,0,0], [0,1,0], [0,0,0] ] The total number of unique paths i…

leetcode_unique_paths_2.cpp

#define MAXN 100
int ans[MAXN][MAXN];

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