Given an index k, return the kth row of the Pascal’s triangle.
For example, given k = 3,
Return [1,3,3,1].
Note:
Could you optimize your algorithm to use only O(k) extra space?
题意:给定k,返回Pascal 三角形的第k行,要求O(k)空间
思路:和Pascal’s Triangle一样,只是不用存所有了……
代码:
public class Solution {
public List getRow(int rowIndex) {
List row = new ArrayList();
for(int i = 0;i < rowIndex + 1;++i){
row.add(0,1);
for(int j = 1;j < row.size() - 1;++j){
row.set(j, row.get(j) + row.get(j + 1));
}
}
return row;
}
}