LeetCode:Triangle

Triangle

Total Accepted: 71791 Total Submissions: 235313 Difficulty: Medium

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.

Subscribe to see which companies asked this question

Hide Tags

 Array Dynamic Programming

思路：

从下往上dp。

c++ code:

class Solution {public:    int minimumTotal(vector<vector<int>>& triangle) {                int n = triangle.size();        vector<int> dp(triangle[n-1]);        for(int layer = n-2;layer >= 0;layer--) {            for(int i=0;i<triangle[layer].size();i++) {                dp[i] = min(dp[i], dp[i+1]) + triangle[layer][i];            }                    }        return dp[0];    }};