/*Given numRows, generate the first numRows of Pascal's triangle.

For example, given numRows = 5,

Return

[

[1],

[1,1],

[1,2,1],

[1,3,3,1],

[1,4,6,4,1]

]*/

/**

* @param {number} numRows

* @return {number[][]}

*/

var generate = function(numRows) {

if(numRows == 0)

return []

if(numRows == 1)

return [[1]]

var arr = [[1]]

i = 1

return generateHelper(arr,i,numRows)

};

var generateHelper = function(arr,i,numRows){

arr[i] = [arr[i-1][0]]

var j = 1

for(; j < arr[i-1].length; j++)

arr[i][j] = arr[i-1][j-1] + arr[i-1][j]

arr[i][j] = arr[i-1][j-1]

if(i+1 == numRows)

return arr

else

return generateHelper(arr,i+1,numRows)

}