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.
Accepted
165,027
Submissions
434,961
class Solution {
public:
int minimumTotal(vector<vector<int>>& triangle)
{
int length=triangle.size();
if(length==0)return 0;
if(length==1)return triangle[0][0];
vector<int> sum=triangle[triangle.size()-1];
for(int i=triangle.size()-2;i>=0;i--)
{
for(int j=0;j<triangle[i].size();j++)
{
sum[j]=min(triangle[i][j]+sum[j],triangle[i][j]+sum[j+1]);
}
}
return sum[0];
}
};
動態規劃自底向上，且以原本的二維矩陣作爲更新的最終矩陣不斷更新，以此減少空間複雜度。