Array-120-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.
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class Solution {
    public int minimumTotal(List<List<Integer>> tri) {
        int row = tri.size();
        int[] count = new int[row];
        
        List<Integer> lastRow = tri.get(row - 1);
        for(int j = 0; j < row; j++)
            count[j] = lastRow.get(j);
        
        for(int i = row - 2; i > -1; i--){
            List<Integer> thisRow = tri.get(i);
            for(int j = 1; j < thisRow.size() + 1; j++){
                count[j - 1] = Math.min(count[j - 1], count[j]) + thisRow.get(j - 1);
            }
        }
        
        return count[0];
    }
}