原题地址：https://oj.leetcode.com/problems/triangle/
题意：
Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.
For example, given the following triangle
[
[2],
[3,4],
[6,5,7],
[4,1,8,3]
]
The minimum path sum from top to bottom
is 11 (i.e., 2 + 3 + 5 + 1 = 11).
Note:
Bonus point if you are able to do this using
only O(n) extra space, where n is the
total number of rows in the triangle.
解题思路：使用动态规划（dp）。需要注意的是从后往前更新！
代码：
class Solution: # @param triangle, a list of lists of integers # @return an integer def minimumTotal(self, triangle): if len(triangle) == 0: return 0 array = [0 for i in range(len(triangle))] array[0] = triangle[0][0] for i in range(1, len(triangle)): for j in range(len(triangle[i]) - 1, -1, -1): if j == len(triangle[i]) - 1: array[j] = array[j-1] + triangle[i][j] elif j == 0: array[j] = array[j] + triangle[i][j] else: array[j] = min(array[j-1], array[j]) + triangle[i][j] return min(array)