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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).
题目解析:
标准DP解法的题, 使用一个数组存结果就可以。
思路是from bottom to top, 先把最后一层存入数组, 然后依次递归上面一层求最小值, 这样最后数组index = 0的位置就是所求. 代码如下:
1 public int minimumTotal(ArrayList<ArrayList<Integer>> triangle) { //标准DP解法, 使用一个数组来存储结果 2 int[] res = new int[triangle.size()]; 3 int lastSize = triangle.size() - 1; 4 for(int i = 0; i < triangle.get(lastSize).size(); i++) 5 res[i] = triangle.get(lastSize).get(i); 6 7 for(int i = triangle.size() - 2; i >= 0; i--){ 8 for(int j = 0; j < triangle.get(i + 1).size() - 1; j++){ 9 res[j] = triangle.get(i).get(j) + Math.min(res[j], res[j + 1]); 10 } 11 } 12 return res[0]; 13 }
Leetcode 120 Triangle (Dynamic Programming Method)
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原文地址：http://www.cnblogs.com/sherry900105/p/4291163.html
