LeetCode Minimum Path Sum

题目：

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://DP     int minPathSum(vector<vector<int> > &grid) {    int m = grid.size();    int n = grid[0].size();    if(m == 0 || n == 0)    return 0;    //初始化     for(int j = 1; j < n; j++)    grid[0][j] += grid[0][j-1];    for(int i = 1; i < m; i++)    grid[i][0] += grid[i-1][0];    for(int i = 1; i < m; i++)for(int j = 1; j < n; j++)grid[i][j] += min(grid[i][j-1], grid[i-1][j]);return grid[m-1][n-1];       }private:int min(int &a, int &b) {return a < b? a : b;}};