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.
class Solution { public: int minimumTotal(vector<vector<int>>& triangle) { int n = triangle.size(); vector<vector<int>> dp(n, vector<int>(n, INT_MAX)); dp[0][0] = triangle[0][0]; for (int i=1; i<n; i++){ for (int j=0; j<=i; j++){ if (j == 0) dp[i][j] = dp[i-1][j] + triangle[i][j]; else if ( j == i) dp[i][j] = dp[i-1][j-1] + triangle[i][j]; else dp[i][j] = min(dp[i-1][j-1]+triangle[i][j], dp[i-1][j]+triangle[i][j]); } } return *min_element(dp[n-1].begin(), dp[n-1].end()); } };
优化：
class Solution { public: int minimumTotal(vector<vector<int>>& triangle) { int n = triangle.size(); vector<int> dp(triangle.back()); for (int i=n-2; i>=0; i--){ for (int j=0; j<=i; j++){ dp[j] = min(dp[j], dp[j+1])+triangle[i][j]; } } return dp[0]; } };
leetcode120 - Triangle - medium
原文：https://www.cnblogs.com/xuningwang/p/13469219.html