[leetcode DP]120. Triangle

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).

从下到上，求每一层每个位置可能的最小的数，套步骤：1，确定最优子问题，2，确定重叠的子问题，3，备忘

class Solution(object):
    def minimumTotal(self, triangle):
        for i in range(len(triangle)-2,-1,-1):
            for j in range(0,len(triangle[i])):
                triangle[i][j] += min(triangle[i+1][j],triangle[i+1][j+1])
        return triangle[0][0]