【LeetCode with Python】 Pascal's Triangle

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原题页面：https://oj.leetcode.com/problems/pascals-triangle/
题目类型：数组
难度评价：★
本文地址：http://blog.csdn.net/nerv3x3/article/details/3465679

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]]

输出帕斯卡三角，明白帕斯卡三角的定义即可简单解题。

class Solution:    # @return a list of lists of integers    def generate(self, numRows):        rows = []        if numRows <= 0:            return rows         if numRows >= 1:            rows.append([1])        if numRows >= 2:            rows.append([1, 1])        if numRows >= 3:            need_rowsnum = numRows - 2            last_row = [1, 1]            for i in range(0, need_rowsnum):                new_row = [1]                for j in range(1, len(last_row)):                    new_row.append(last_row[j - 1] + last_row[j])                new_row.append(1)                rows.append(new_row)                last_row = new_row        return rows