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