class Solution { func uniquePaths(_ m: Int, _ n: Int) -> Int { var dp = Array(repeating: Array(repeating: 1, count: n), count: m) for i in 1..<m { for j in 1..<n { dp[i][j] = dp[i-1][j] + dp[i][j-1] } } return dp[m-1][n-1] } }