LeetCode 之 Triangle

Posted 2020-08-20

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.

 

给定一个三角形，求最小路径。每层只能选一个整数，上一层和下一层的数必须是相邻的。

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