Title:
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:开始以为是贪心,其实并不是,是动态规划。倒过来想,从底向上,转移方程 f[i][j] += min(f[i+1][j],f[i+1][j+1]). 空间复杂度O(1)
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]; } };