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