LeetCode: 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.

   typedef vector<vector<int> > vvi;  
   typedef vector<int> vi;  
   #define INT_MAX 0x7FFFFFFF

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