题目：
给定一个只含非负整数的m*n网格，找到一条从左上角到右下角的可以使数字和最小的路径。
注意事项
你在同一时间只能向下或者向右移动一步
class Solution {
public:
/**
* @param grid: a list of lists of integers.
* @return: An integer, minimizes the sum of all numbers along its path
*/
int minPathSum(vector<vector<int> > &grid) {
// write your code here
int m = grid.size();
int n = grid[0].size();
int dp[m][n];
dp[0][0] = grid[0][0];
for (int i = 1; i < m; i++)
dp[i][0] = dp[i-1][0] + grid[i][0];
for (int j = 1; j < n; j++)
dp[0][j] = dp[0][j-1] + grid[0][j];
for (int i = 1; i < m; i++)
for (int j = 1; j < n; j++)
dp[i][j] = min(dp[i-1][j], dp[i][j-1]) + grid[i][j];
return dp[m-1][n-1];
}
};