uniquePathsWithObstacles

uniquePathsWithObstacles.swift

class Solution {
    func uniquePathsWithObstacles(_ obstacleGrid: [[Int]]) -> Int {
        var grid = obstacleGrid
        let row = grid.count
        let col = grid[0].count
        //Base case
        if grid.isEmpty || grid[0][0] == 1 { return 0 }
        grid[0][0] = 1
        for i in 1..<row {
            grid[i][0] = (grid[i][0] == 0 && grid[i-1][0] == 1) ? 1 : 0
        }
         for j in 1..<col {
            grid[0][j] = (grid[0][j] == 0 && grid[0][j - 1] == 1) ? 1 : 0
        }
        for i in 1..<row {
            for j in 1..<col {
                if grid[i][j] == 0 {
                    grid[i][j] = grid[i-1][j] + grid[i][j-1]
                } else {
                    grid[i][j] = 0
                }
            }
        }
        return grid[row - 1][col - 1]
    }
}