Leetcode 63 Solution

This article provides solution to leetcode question 63 (unique-paths-ii)
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https://leetcode.com/problems/unique-paths-ii

Solution

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m = obstacleGrid.size();

        if (m == 0)
            return 0;

        int n = obstacleGrid[0].size();

        vector<vector<int>> a;
        for (int i = 0; i < m; i++)
            a.push_back(vector<int>(n));

        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
            {
                if (obstacleGrid[i][j] == 1)
                    a[i][j] = 0;
                else if (i == 0 && j == 0)
                    a[i][j] = 1;
                else
                {
                    int s = 0;

                    if (i > 0 && obstacleGrid[i - 1][j] == 0)
                        s += a[i - 1][j];

                    if (j > 0 && obstacleGrid[i][j - 1] == 0)
                        s += a[i][j - 1];

                    a[i][j] = s;
                }
            }
        }

        return a[m - 1][n - 1];
    }
};