Leetcode 118 Pascal's Triangle

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]

]

转移方程 p[i][j] = p[i-1][j-1] + p[i-1][j]

var generate = function(numRows) {

    var p = []

    for (var i=0;i<numRows;i++){

        p.push(Array(i+1))

        p[i][0] = p[i][i] = 1

        for (var j=1;j<i;j++)

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

    }

    return p

}