LeetCode Triangle 120 DP问题

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, wheren is the total number of rows in the triangle.

class Solution {
public:
int minimumTotal(vector<vector<int> > &triangle) {
int i,j;
for(i=triangle.size()-2;i>=0;i--)
{
for(j=0;j<i+1;j++)
triangle[i][j]=min(triangle[i+1][j],triangle[i+1][j+1]);

}
return triangle[0][0];

}
};