119. Pascal's Triangle II(杨辉三角简单变形)

2019-03-14 13:04:09 浏览数 (1)

Pascal's Triangle II

【题目】

Given a non-negative index k where k ≤ 33, return the kth index row of the Pascal's triangle.

Note that the row index starts from 0.

(翻译:给定一个非负索引 k,其中 k ≤ 33,返回杨辉三角的第 行。)

In Pascal's triangle, each number is the sum of the two numbers directly above it.

(在杨辉三角中,每个数是它左上方和右上方的数的和。)

Example:

代码语言:javascript复制
Input: 3
Output: [1,3,3,1]

【分析】

只是我上一篇博客题目的简单变形,此题更为简单,还是用ArrayList 暴力求解,Java实现代码如下:

代码语言:javascript复制
class Solution {
    public List<Integer> getRow(int rowIndex) {
        List<Integer> row = new ArrayList<>();
        if (rowIndex < 0) return row;
        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;
    }
}

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