leetcode 120: Triangle

class Solution {
public:
int minimumTotal(vector<vector<int>>& triangle) {
vector<int> last(1,triangle[0][0]);
for(int i=1;i<triangle.size();i++)
{
vector<int> curr(i+1,0);
for(int j=0;j<triangle[i].size();j++)
{
if(j==0)
curr[j]=last[j]+triangle[i][j];
else if(j==triangle[i].size()-1)
curr[j]=last[j-1]+triangle[i][j];
else
curr[j]=min(last[j-1],last[j])+triangle[i][j];
}
last=curr;
}
int min=INT_MAX;
for(int i=0;i<last.size();i++)
if(last[i]<min)
min=last[i];
return min;
}
};