[leetcode]120. Triangle

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).

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.

 

class Solution(object):
    def minimumTotal(self, triangle):
        curMinList = triangle[-1]
        
        for level in range(len(triangle)-2,-1,-1):
            nextList = curMinList
            curMinList = []
            curList = triangle[level]
            for i , num in enumerate(curList):
                curMinList.append( min(num+nextList[i],num+nextList[i+1]))
        
        return curMinList[0]
        

 

더 깔끔한 코드

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