minimum path sum (similar to unique path)

def minPathSum(self,grid):
        if len(grid) == 0 or len(grid[0]) == 0:
            return 0
        solution = [grid[i][:] for i in range(len(grid))]
        for i in range(len(grid)):
            for j in range(len(grid[0])):
                if i == 0 and j > 0:
                    solution[i][j] += solution[i][j-1]
                elif j == 0 and i > 0:
                    solution[i][j] += solution[i-1][j]
                elif i > 0 and j > 0:
                    solution[i][j] += min(solution[i-1][j],solution[i][j-1]) 
        return solution[len(grid)-1][len(grid[0])-1]