Leetcodeの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

[
     [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.
コード:

class Solution {
public:
    int minimumTotal(vector>& triangle) {
        int len = triangle.size();
	int *v = new int[len];
	for (int i = 0; i < len; i++) {
		v[i] = triangle[len - 1][i];
	}

	for (int i = len - 2; i >= 0; i--) {
		int len1 = triangle[i].size();
		for (int j = 0; j < len1; j++) {
			int add = v[j] > v[j + 1] ? v[j + 1] : v[j];
			v[j] = triangle[i][j] + add;
		}
	}
	int res = v[0];
	delete[] v;
	return res;
    }
};