0063-unique-paths-ii.cpp

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        int f[m][n];
        
        for (int i = 0; i < m; ++i) {
            for (int j = 0; j < n; ++j) {
                if (obstacleGrid[i][j] == 1) {
                    f[i][j] = 0;
                } else if (i == 0 && j == 0) {
                    f[i][j] = 1;
                } else if (i == 0) {
                    f[i][j] = f[i][j - 1];
                } else if (j == 0) {
                    f[i][j] = f[i - 1][j];
                } else {
                    if (f[i - 1][j] > 0x7fffffff - f[i][j - 1]) {
                        f[i][j] = 0x7fffffff;
                    } else {
                        f[i][j] = f[i - 1][j] + f[i][j - 1];
                    }
                }
            }
        }
        
        return f[m - 1][n - 1];
    }
};