118. 杨辉三角

简单的杨辉三角

func generate(_ numRows: Int) -> [[Int]] {
        
        var array =  [[Int]]()
        var lastArray = [Int]()

        for i in 1...numRows {
            
            var tempArray = Array(repeating: 1, count:i)
            if(i > 2){
                
                for j in 0..<lastArray.count - 1{
                    tempArray[j+1] = lastArray[j] + lastArray[j + 1]
                }
                
            }
            
            lastArray = tempArray;
            
            array.append(tempArray)
            
        }
        
        return array
        
        
    }