Problem Pascal's Triangle

Problem Description:

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]
]

 

 

 Solution:
 1     public List<List<Integer>> generate(int numRows) {
 2 List<List<Integer>> triangle  = new ArrayList<List<Integer>>();
 3         for (int i = 0; i < numRows; i++) {
 4             List<Integer> row = new ArrayList<Integer>();
 5             for (int j = 0; j <= i; j++) {
 6                 if (j == 0 || j == i) {
 7                     row.add(1);
 8                 } else {
 9                     row.add(triangle.get(i-1).get(j-1) + triangle.get(i-1).get(j));
10                 }
11             }
12 
13             triangle.add(row);
14         }
15 
16         return triangle;
17     }

 

posted @ 2014-06-29 15:04  HaruHaru  阅读(132)  评论(0)  编辑  收藏  举报