【leetcode】Triangle

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

The minimum path sum from top to bottom is 11 (i.e., 2 + 3 + 5 + 1 = 11).
思路：
很明显就是动态规划的题目；
最优子结构为res[j]=min(res[j-1],res[j])+triangle[i][j];
表示记录到达本行第j个数字时的最小值。

class Solution {public:    int minimumTotal(vector<vector<int> > &triangle) {        int n=triangle.size();        if(n==0) return 0;        int *res;        res=(int *)malloc(n*sizeof(int));        memset(res,0,n*sizeof(int));        res[0]=triangle[0][0];//res[j]记录到达本行第j个数字时的最小值        for(int i=1;i<n;i++)            for(int j=triangle[i].size()-1;j>=0;j--)            {                if(j==0)                    res[j]=res[j]+triangle[i][j];                else if(j==triangle[i].size()-1)                    res[j]=res[j-1]+triangle[i][j];                else                    res[j]=min(res[j-1],res[j])+triangle[i][j];            }        int minres=INT_MAX;        for(int i=0;i<n;i++)        {            minres=min(res[i],minres);        }        return minres;    }};