Leetcode#63 Unique Paths II

原题地址

 

基本动态规划题

 

代码：

int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
        if (obstacleGrid.empty() || obstacleGrid[0].empty()) return 0;
        
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        vector<int> sum(n, 0);
        
        sum[n - 1] = 1;
        for (int i = m - 1; i >= 0; i--) {
            sum[n - 1] = obstacleGrid[i][n - 1] > 0 ? 0 : sum[n - 1];
            for (int j = n - 2; j >= 0; j--)
                sum[j] = obstacleGrid[i][j] > 0 ? 0 : sum[j] + sum[j + 1];
        }
                
        return sum[0];
}