【leetcode】triangle（easy)

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).

 

思路：

自底向上，存当前数字加下面两个中比较小的数字，最后顶上的数字就是答案了。不难，直接AC

class Solution {
public:
    int minimumTotal(vector<vector<int> > &triangle) {
        vector<vector<int>> data(triangle.size(), vector<int>());
        data[data.size() - 1] = triangle[triangle.size() - 1];
        for(int i = triangle.size() - 2; i >= 0; i--)
        {
            for(int j = 0; j < triangle[i].size(); j++)
            {
                int min = (data[i + 1][j] < data[i + 1][j + 1]) ? data[i + 1][j] : data[i + 1][j + 1]; 
                data[i].push_back(min + triangle[i][j]);
            }
        }
        return data[0][0];
    }