Minimum Path Sum

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

You can only move right or down at any point.

Example 1:

Input:
grid = [[1,3,1],
         [1,5,1],
         [4,2,1]]
Output: 7
Explanation: Path 1→3→1→1→1 = 7

Example 2:

Input:  grid = [[1,2,3],[4,5,6]]
Output: 12

Constraints:

• m == grid.length, n == grid[i].length
• 1 <= m, n <= 200
• 0 <= grid[i][j] <= 200