LeetCode-Minimum Path Sum

题目要求：
相比较于unique path，寻找一条最短路径，仍然采用动态规划：
Method: flag[i][j] = grid[i][j]+(flag[i-1][j] < flag[i][j-1]? flag[i-1][j]:flag[i][j-1]);
源码如下：

class Solution {
public:
    void non_uniqpath(vector<vector<int>>& grid,int& num){
        int m = grid.size();
        int n = grid[0].size();
        vector<vector<int>> flag;
        flag.resize(m);
        for_each(flag.begin(),flag.end(),[n](vector<int>& pa){pa.resize(n,0);});
        flag[0][0] = grid[0][0];
        for (int i=1;i<n;i++){
            flag[0][i] = grid[0][i] + flag[0][i-1];
        }
        for (int i=1;i<m;i++){
            flag[i][0] = grid[i][0] + flag[i-1][0];
        }
        for (int i=1;i<m;i++){
            for (int j=1;j<n;++j){
                flag[i][j] = grid[i][j]+(flag[i-1][j] < flag[i][j-1]? flag[i-1][j]:flag[i][j-1]);
            }
        }
        num = flag[m-1][n-1];
    }
    
    int minPathSum(vector<vector<int>>& grid) {
        int num=0;
        non_uniqpath(grid,num);
        return num;
    }
};