letcode 118

问题描述：
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]
]

import java.util.*;
class Solution {
public List<List<Integer>> generate(int numRows) {
List<List<Integer>> list=new ArrayList<List<Integer>>();
for(int i=0;i<=numRows-1;i++)
{
long num=1;
ArrayList<Integer> al=new ArrayList<Integer>();
for(int j=0;j<=i;j++)
{
al.add((int)num);
num=num*(i-j)/(j+1);
}
list.add(al);
}
return list;
}
}

class Test118
{
public static void main(String[] args)
{
Solution s=new Solution();
System.out.println(s.generate(5));
}
}