class Solution {
  public:
    vector <vector <int> > *t;     // I make this a pointer so that I'm not making a copy of triangle.
    int minimumTotal(vector<vector<int>>& triangle);
    int dp(int row, int col);
};

int Solution::minimumTotal(vector<vector<int>>& triangle)
{
    size_t i;
    
    t = &triangle;
    return dp(0, 0);
}

/* Here is a straightforward implementation of the recursive solution. */

int Solution::dp(int row, int col)
{
    int z, o, answer;
    
    /* Base case is when we're at the last row of the triangle. */

    if (row == t->size()-1) return (*t)[row][col];

    /* Otherwise, we make the two recursive calls and add the minimum
       to our triangle entry. */

    z = dp(row+1, col);
    o = dp(row+1, col+1);
    answer = (*t)[row][col] + ((z < o) ? z : o);
    return answer;
}