LeetCode (Triangle)

Problem:

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.

Solution:

class Solution {public:    int minimumTotal(vector<vector<int>>& triangle) {        int n = triangle.size();        for(int i = 1; i < n; i++){            triangle[i][0] += triangle[i - 1][0];            for(int j = 1; j < triangle[i].size() - 1; j++){                triangle[i][j] = min(triangle[i][j] + triangle[i - 1][j - 1], triangle[i][j] + triangle[i - 1][j]);            }            triangle[i].back() += triangle[i - 1].back();        }        return *min_element(triangle[n - 1].begin(), triangle[n - 1].end());    }};