119.Pascal's Triangle II

题目描述

Given an index k, return the k^th row of the Pascal’s triangle.

For example, given k = 3,

Return

[1,3,3,1].

本题k=0,返回[1]

解题

思路

每一行除了第0个元素和最后一个元素除外，current[j] = lastRow[j-1]+lastRow[j];

代码

public List<Integer> getRow(int rowIndex) {
        List<Integer> pre = new ArrayList<Integer>();
        pre.add(0,1);

        for (int i = 0; i<rowIndex; i++) {
            List<Integer> tempLists =new ArrayList<Integer>();
            tempLists.add(0,1);
            for (int j = 1; j <=i;j++) {
                tempLists.add(j,pre.get(j-1)+pre.get(j));
            }
            tempLists.add(1);
            pre = tempLists;
        }
        return pre;
    }