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.
DP： 从下往上走， 从左向右走 6处的答案是 4 和 1的最小值 + 6， 5处的答案是1 和 8的最小值 + 5 。。。。。。
class Solution { public int minimumTotal(List<List<Integer>> triangle) { int n = triangle.size(); int[] result = new int[n + 1]; for (int i = n - 1; i >= 0; i--) { for (int j = 0; j < triangle.get(i).size(); j++) { result[j] = triangle.get(i).get(j) + Math.min(result[j], result[j + 1]); } } return result[0]; } }