118. Pascal's Triangle

Given numRows, generate the first numRows

For example, given numRows = 5,
Return

[ 

     [1], 

    [1,1], 

   [1,2,1], 

  [1,3,3,1], 

 [1,4,6,4,1] 

]

题意：打印杨辉三角形
思路：用list辅助存储，写得很水

import java.util.ArrayList;

public class Solution {
    public List<List<Integer>> generate(int numRows) {
        List<List<Integer>> resultList = new ArrayList<List<Integer>>();
        if(numRows == 0) {
            return resultList;
        }
        List<Integer> list = new ArrayList<Integer>();
        list.add(1);
        resultList.add(list);
        for(int i = 1; i < numRows; i++) {
            List<Integer> temp = resultList.get(i - 1);
            list = new ArrayList<Integer>();
            list.add(1);
            for(int j = 1; j <= i - 1; j++) {
                int m = temp.get(j - 1) + temp.get(j);   
                list.add(m);
            }
            list.add(1);
            resultList.add(list);
        }
        return