leetcode_64. Minimum Path Sum

題目：

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.

跟上次的題目很像，就是多了權值條件而已。那就每個位置等於上面或者左面加自己，上面或者左面哪個小用哪個加自己。

比較簡單，代碼如下：

class Solution {
public:
    int minPathSum(vector<vector<int>>& grid) {
        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];
    }
};

要先初始化一下。