Triangle

Algorithm : DP;

 

public class Solution
{
    public int minimumTotal(ArrayList<ArrayList<Integer>> triangle)
    {
        for(int i = triangle.size()-2; i>=0;i--)
        {
            ArrayList<Integer> a1 = triangle.get(i);
            ArrayList<Integer> nextLevel = triangle.get(i+1);
            for(int j = 0; j<a1.size();j++)
            {
                int sum2=0,sum3=0;
                sum2 = a1.get(j) + nextLevel.get(j);
                sum3 = a1.get(j) + nextLevel.get(j+1);
                a1.set(j, Math.min(sum2,sum3));
            }
        }
        
        return triangle.get(0).get(0);
    }
}