Leetcode - Triangle Solution
Poor Man
- Published
- Updated
- Reading time
- 1 min read
- Length
- 208 words
Given a triangle array, return the minimum path sum from top to bottom.
For each step, you may move to an adjacent number of the row below. More formally, if you are on index i on the current row, you may move to either index i or index i + 1 on the next row.
Example 1:
Text
Input: triangle = [[2],[3,4],[6,5,7],[4,1,8,3]]
Output: 11
Explanation: The triangle looks like:
2
3 4
6 5 7
4 1 8 3
The minimum path sum from top to bottom is 2 + 3 + 5 + 1 = 11 (underlined above).Example 2:
Text
Input: triangle = [[-10]]
Output: -10Constraints:
1 <= triangle.length <= 200triangle[0].length == 1triangle[i].length == triangle[i - 1].length + 1-104 <= triangle[i][j] <= 104
Follow up: Could you do this using only O(n) extra space, where n is the total number of rows in the triangle?
Solution in python#
Python
class Solution:
def minimumTotal(self, triangle: List[List[int]]) -> int:
for i in range(1,len(triangle)):
triangle[i][ 0] += triangle[i-1][ 0]
triangle[i][-1] += triangle[i-1][-1]
for j in range(1,len(triangle[i])-1):
triangle[i][j] += min(triangle[i-1][j-1], triangle[i-1][j])
return min(triangle.pop())