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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.
算法思路：
思路1：
自上而下，用一个数组记录从根节点到第 i 层的所有节点的加权之后的情况，跌倒到最后一层时，即可求出最短路径。需要O(n)空间。
不再实现
思路2：
1 public int minimumTotal(List<List<Integer>> triangle) { 2 if(triangle == null || triangle.size() == 0) return 0; 3 int height = triangle.size(); 4 for(int i = height - 2; i >= 0; i--){ 5 List<Integer> list = triangle.get(i); 6 for(int j = 0; j < list.size();j++){ 7 int min = triangle.get(i + 1).get(j) < triangle.get(i + 1).get(j + 1) ? triangle.get(i + 1).get(j) : triangle.get(i + 1).get(j + 1); 8 list.set(j, list.get(j) + min); 9 } 10 } 11 return triangle.get(0).get(0); 12 }
这代码是之前看到的，很厉害。
[leetcode]Triangle,布布扣,bubuko.com
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原文地址：http://www.cnblogs.com/huntfor/p/3859567.html
