LeetCode-120-Triangle
阿新 • • 發佈:2019-02-05
code 問題 umt 定向 owin etc 情況 spa row
算法描述:
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).
解題思路:動態規劃題,遞推式為:dp[i][j] = min(dp[i+1][j], dp[i+1][j+1]) + triangle[i][j];這道題用自底向上比較容易。(自定向上需要考慮的邊界問題比較多,遞推式為:dp[i][j]=min(dp[i-1][j],dp[i-1][j-1])+triangle[i][j], 需要討論 j=0 和j=i 兩種特殊情況)
int minimumTotal(vector<vector<int>>& triangle) { vector<int> dp(triangle.back()); for(int i = triangle.size()-2; i >=0; i--){ for(int j =0; j <triangle[i].size(); j++){ dp[j] = min(dp[j],dp[j+1]) + triangle[i][j]; } }return dp[0]; }
LeetCode-120-Triangle