Pascal's Triangle (Swift)

pascals-triangle.swift

import Foundation

class Solution {
    func generate(_ numRows: Int) -> [[Int]] {
        var result = [[Int]]()

        for i in 0..<numRows {
            var array = Array(repeating: 1, count: i + 1)
            if i > 1 {
                let previousArray = result[i-1]
                for j in 1...i-1 {
                    array[j] = previousArray[j-1] + previousArray[j]
                }
            }
            result.append(array)
        }
        return result
    }
}

let solution = Solution()

//     1
//    1 1
//   1 2 1
//  1 3 3 1
// 1 4 6 4 1
print(solution.generate(5))

// 1
print(solution.generate(1))

//  1
// 1 1
print(solution.generate(2))

//   1
//  1 1
// 1 2 1
print(solution.generate(3))