[LeetCode]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.

思考：动态规划。

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