Unique Paths

unique_paths_with_obstacles.swift

class Solution {
    func uniquePathsWithObstacles(_ obstacleGrid: [[Int]]) -> Int {
        
        if obstacleGrid[0][0] == 1 { return 0}
        
        let n = obstacleGrid.count, m = obstacleGrid[0].count
        var dp = Array(repeating: Array(repeating:0, count: m), count:n)
        dp[0][0] = 1
        
        for i in 0..<n{
            for j in 0..<m {
                let element = obstacleGrid[i][j]
                
                if element == 1 || (i == 0 && j == 0) {
                    continue
                }
                var total = 0
                if i > 0 {
                    total += dp[i - 1][j]
                }
                
                if j > 0 {
                    total += dp[i][j - 1]
                }
                
                dp[i][j] = total
            }
        }
        return dp[n - 1][m - 1]
    }
}