leetcode 118. Pascal's Triangle

Given a non-negative integer *numRows*, generate the first*numRows*of Pascal's triangle.

In Pascal's triangle, each number is the sum of the two numbers directly above it.

 

 

Input: 5
Output:
[
     [1],
    [1,1],
   [1,2,1],
  [1,3,3,1],
 [1,4,6,4,1]
]

 

 

var generate = function(numRows) {
    var ans = [];
    for(var i=0;i