[leetcode]Pascal's Triangle

新博文地址：[leetcode]Pascal's Triangle

 

http://oj.leetcode.com/problems/pascals-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]
]

跟杨辉三角略像啊，我的想法很直接，逐行求解，存储，如果有好的方法，请分享一下

 

 public ArrayList<ArrayList<Integer>> generate(int numRows){
		ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
		if(numRows <= 0){
			return result;
		}
		int[] array = {1};
		for(int i = 1; i < numRows; i++){
			result.add(convertToList(array));
			array = getNextList(array);
		}
		result.add(convertToList(array));
		return result;
	}
	private ArrayList<Integer> convertToList(int[] array){
		ArrayList<Integer> list = new ArrayList<Integer>();
		for(int tem : array){
			list.add(tem);
		}
		return list;
	}
	private int[] getNextList(int[] array){
		int[] result = new int[array.length + 1];
		result[0] = 1;
		result[array.length] = 1;
		for(int i = 0; i <= array.length - 2; i++){
			result[i + 1] = array[i] + array[i + 1];
		}
		return result;		
	}