Pascal's Triangle

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

输入格式

A single integer numRows (0≤numRows≤30).

输出格式

Output a compact JSON 2D integer array; output [] when numRows=0.

样例 1

输入：

0

输出：

[]

样例 2

输入：

5

输出：

[[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

样例说明

Build each new row from the sums of adjacent elements in the previous row.