[数据结构与算法]动态规划notebook

63. 不同路径 II

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        vector<vector<int>> map(m, vector<int>(n, 0));

        for (int i = 0; i < m && obstacleGrid[i][0] == 0; ++i)
            map[i][0] = 1;
        
        for (int j = 0; j < n && obstacleGrid[0][j] == 0; ++j) 
            map[0][j] = 1;

        for (int i = 1; i < m; ++i) {
            for (int j = 1; j < n; ++j) {
                if (obstacleGrid[i][j] == 1) continue;

                map[i][j] = map[i - 1][j] + map[i][j - 1];
            }
        }
        return map[m - 1][n - 1];
    }
};

小结

• 遇到障碍dp[i][j]保持0就可以了