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

<p><strong>Note:</strong> You can only move either down or right at any point in time.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/minpath.jpg" style="width: 242px; height: 242px;" />
<pre>
<strong>Input:</strong> grid = [[1,3,1],[1,5,1],[4,2,1]]
<strong>Output:</strong> 7
<strong>Explanation:</strong> Because the path 1 &rarr; 3 &rarr; 1 &rarr; 1 &rarr; 1 minimizes the sum.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1,2,3],[4,5,6]]
<strong>Output:</strong> 12
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 200</code></li>
	<li><code>0 &lt;= grid[i][j] &lt;= 200</code></li>
</ul>

class Solution:
    def minPathSum(self, grid: List[List[int]]) -> int:
        n_rows = len(grid)
        n_cols = len(grid[0])
        def get_val(row, col):
            return grid[row][col]
        def valid_neighbors(points):
#            print(points)
            acc = []
            point = points[0]
            if point[0] + 1 < n_rows:
                acc.append( [point[0] + 1, point[1]] )
                acc[-1].append(point[2] + get_val(*acc[-1]))
            if len(points) > 1:
                for i in range(len(points) - 1):
                    point1, point2 = points[i:(i + 2)]
                    acc.append( [point1[0], point2[1], min(point1[2], point2[2]) + get_val(point1[0], point2[1])] )
            point = points[-1]
            if point[1] + 1 < n_cols:
                acc.append( [point[0], point[1] + 1] )
                acc[-1].append(point[2] + get_val(*acc[-1]))
            if len(acc) == 1:
                return acc[0][2]
            return valid_neighbors(acc)
        if n_rows == 1:
            if n_cols == 1:
                return grid[0][0]
            else:
                return sum(grid[0])
        elif n_cols == 1:
            return sum(map(lambda x: x[0], grid))
        return valid_neighbors( [[0, 0, get_val(0, 0)]] )
22800