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. Solution-