Topic

• Array

Description

https://leetcode.com/problems/pascals-triangle-ii/

Given an integer rowIndex, return the rowIndexth row of the Pascal’s triangle.

Notice that the row index starts from 0.

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

Follow up:

Could you optimize your algorithm to use only O(k) extra space?

Example 1:

Input: rowIndex = 3 Output: [1,3,3,1]

Example 2:

Input: rowIndex = 0 Output: [1]

Example 3:

Input: rowIndex = 1 Output: [1,1]

Constraints:

• 0 <= rowIndex <= 33

Analysis

略

Submission

import java.util.LinkedList; import java.util.List;public class PascalsTriangleII {public List<Integer> getRow(int rowIndex) {List<Integer> result = new LinkedList<Integer>();if(rowIndex < 0) return result;for(int i = 0; i <= rowIndex; i++) {result.add(0, 1);for(int j = 1 ; j < result.size() - 1; j++) result.set(j, result.get(j) + result.get(j + 1));}return result;} }

Test

import static org.junit.Assert.*; import static org.hamcrest.CoreMatchers.*;import java.util.ArrayList; import java.util.Arrays;import org.junit.Test;public class PascalsTriangleIITest {@Testpublic void test() {PascalsTriangleII obj = new PascalsTriangleII();assertThat(obj.getRow(3), is(new ArrayList<>(Arrays.asList(1, 3, 3, 1))));assertThat(obj.getRow(0), is(new ArrayList<>(Arrays.asList(1))));assertThat(obj.getRow(1), is(new ArrayList<>(Arrays.asList(1, 1))));assertThat(obj.getRow(4), is(new ArrayList<>(Arrays.asList(1, 4, 6, 4, 1))));} } 創作挑戰賽新人創作獎勵來咯，堅持創作打卡瓜分現金大獎

總結

以上是生活随笔為你收集整理的LeetCode - Easy - 119. Pascal‘s Triangle II的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。