链表中正元素的总和

Question

我需要编写程序，但我无法完成它并弄乱了方法。 目的是找到所有正元素的总和并将其添加到最后。我刚刚开始教授课程和方法。

如何计算最终数组中所有正元素的总和？

这是我的代码：

class Node

    attr_accessor :value, :next_node

    def initialize val,next_in_line
        @value = val
        @next_nodex = next_in_line
        puts "Initialized a Node with value:  " + value.to_s 
    end
end

class LinkedList

    def initialize val
        @head = Node.new(val,nil)
    end

    def add(value)
        current = @head
        while current.next_node != nil
            current = current.next_node
        end 
        current.next_node = Node.new(value,nil)
        self    
    end

    def delete(val)
        current = @head
        if current.value == val
            @head = @head.next_node
        else
            current = @head
            while (current != nil) && (current.next_node != nil) && ((current.next_node).value != val)
                current = current.next_node
            end 

            if (current != nil) && (current.next_node != nil)
                current.next_node = (current.next_node).next_node
            end
        end
    end

    def display
        current = @head
        full_list = [] 
        while current.next_node != nil 
            full_list += [current.value.to_s]
            current = current.next_node
        end
        full_list += [current.value.to_s]
        puts full_list.join(" ")
    end
    def sum

    end
end


puts "\n"
list = [*-99..99].shuffle
ll = LinkedList.new(list[0])

(1..9).each do |i|
   ll.add(list[i])
end

puts "\nDo you want item to add? '1' - yes '0' - no"
adding = gets.to_i
puts "\n"
if adding == 1
    ll.add(list[10])
    end


puts "\nDisplaying Linked List:"
ll.display

puts "\nDo you want to delete item? '1' - yes '0' - no"
deleting = gets.to_i

if deleting == 1   
puts "Type in and delete item and then display the linked list:"
deleteInt = gets.to_i
ll.delete(deleteInt)
 end
puts ll.display

puts "\nThe sum of all positive elements"
ll.sum

Answer 1

首先，您在 Node.initialize 方法中输入错误 - 我认为 @next_nodex 应该是 @next_node。其次，不要在最后使用puts 2次：puts ll.display。要添加数组，最好使用<< 符号。

另一件事，我看不出display 和sum 方法之间的任何概念差异，除了一个条件。据此，应该是这样的：

def sum
  current = @head
  sum = 0
  while current.next_node != nil
    sum += current.value if current.value > 0
    current = current.next_node
  end
  sum += current.value if current.value > 0
  sum
end

或干：

def full_list
  current = @head
  full_list = []
  while current.next_node != nil
    full_list << current.value
    current = current.next_node
  end
  full_list << current.value
  full_list
end

def display
  puts full_list.join(' ')
end

def sum
  full_list.keep_if { |x| x > 0 }.reduce(:+)
end

All code