119. 杨辉三角 II

 1 class Solution(object):
 2     def getRow(self, rowIndex):
 3         """
 4         :type rowIndex: int
 5         :rtype: List[int]
 6         """
 7         a = []
 8         # 初始化
 9         for i in range(1, rowIndex + 2):
10             a.append([0] * i)
11         # 最顶端元素
12         a[0][0] = 1
13         for i in range(1, rowIndex+1):
14             for j in range(i + 1):
15                 # 每一行第一个和最后一个元素都是1
16                 if j == i or j == 0:
17                     a[i][j] = 1
18                 # 否则是肩上两个元素之和
19                 else:
20                     a[i][j] = a[i - 1][j] + a[i - 1][j - 1]
21         # 返回最后一个list
22         return a[-1]
23 
24 
25 if __name__ == ‘__main__‘:
26     solution = Solution()
27     print(solution.getRow(3))