LeetCode 63. Unique Paths II

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描述

从左上走到右下右多少种走法，中间可能有障碍物

解决

动态规划，把存答案的数组初始化所有为0，然后从左到右，从上往下遍历下去即可

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

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