leetcode: Minimum Path Sum

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.

Note: You can only move either down or right at any point in time.

class Solution {public:        int min(int a, int b)    {        if (a <= b)            return a;                    return b;    }        int minPathSum(vector<vector<int> > &grid) {            int n = grid.size();        int m = grid[0].size();        vector<vector<int> > dpGrid(n, vector<int>(m));                dpGrid[0][0] = grid[0][0];        for (int i=1; i<n; i++)        {            dpGrid[i][0] = dpGrid[i-1][0]+grid[i][0];        }                for (int j=1; j<m; j++)        {            dpGrid[0][j] = dpGrid[0][j-1]+grid[0][j];        }                for (int j=1; j<m; j++)        {            for (int i=1; i<n; i++)            {                dpGrid[i][j] = min(dpGrid[i-1][j], dpGrid[i][j-1])+grid[i][j];            }        }                return dpGrid[n-1][m-1];    }};