[leetcode]Triangle @ Python
2679 ワード
原題住所:https://oj.leetcode.com/problems/triangle/
タイトル:
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
The minimum path sum from top to bottom is
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.
解題構想:ダイナミックプランニング(dp)を使用する.注意が必要なのは後から前へ更新!
コード:
タイトル:
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.
解題構想:ダイナミックプランニング(dp)を使用する.注意が必要なのは後から前へ更新!
コード:
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)