（难度Medium） Problem 120. Triangle（三角矩形最小路径和）

Triangle

Medium

## Description

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.