120. Triangle【M】【95】【leetcode】

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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.

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对于题目给的输入，每次存从顶到当前节点的最小值

保留两行即可

class Solution(object):    def minimumTotal(self, triangle):        t = triangle        l = len(t)        if l == 1 :            return t[0][0]        res1 = [99999] * l        res2 = [99999] * l        res1[0] = t[0][0]        for i in range(1,l):            res2[0] = res1[0] + t[i][0]            #print res1,res2            for j in range(1,len(t[i])):                #print i,j,t[i][j],res1[j-1],res1[j]                res2[j] = min(res1[j],res1[j - 1]) + t[i][j]            #print res1,res2            res1 = res2[:]        return min(res2)

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