What is bubble sort?

Algorithm that compares adjacent numbers and exchanges according to conditions This time, we will implement by comparing from the right side of the sequence and arranging in ascending order.

bubbleSort.rb

code

#Bubble sort

def bubbleSort(num)
  len = num.length                           #Stores the length of a sequence
  len.times do |i|                           #Loop for the length of the sequence
    (len - 1).downto(i+1) do |j|             #Sequence length-1～i+Loop to 1
      if num[j]  < num[j-1]                  #Compare the innermost part of the sequence with the one before it.
        num[j], num[j-1] = num[j-1], num[j]  #If the number in the back is smaller, replace it
      end
    end
    puts "#{i+1}Time;#{num.join(" ")}"       #output
  end
end

puts "Enter numbers"
number = gets.split().map(&:to_i)             #Store the entered number in an array as an int type
bubbleSort(number)                            #Run

Run

Enter numbers
5 9 3 1 2 8 4 7 6
1st time; 1 5 9 3 2 4 8 6 7
2nd time; 1 2 5 9 3 4 6 8 7
3rd time; 1 2 3 5 9 4 6 7 8
4th time; 1 2 3 4 5 9 6 7 8
5th time; 1 2 3 4 5 6 9 7 8
6th time; 1 2 3 4 5 6 7 9 8
7th time; 1 2 3 4 5 6 7 8 9
8th time; 1 2 3 4 5 6 7 8 9
9th time; 1 2 3 4 5 6 7 8 9

Maybe this is right ... This time from the back of the array. In short, I sorted in order from the numbers I put in later. Therefore, instead of repeating with times as usual, I tried using downto.

downto method

downto(min) {|n| ... } -> self Repeat the block, decrementing from self to min by 1. If self <min, do nothing. .. [Reference: Ruby 2.7.0 Reference Manual]

Finally

It seems that various implementations can be made by changing the conditions, and it was fun to write. Is it unique to Ruby to replace the elements of an array? I felt like it was, but I couldn't compare it because I didn't understand other languages.

I feel that it will be possible to speed up execution and simplify the code under the same conditions, so please lend me the wisdom of all the experts.

Tomorrow we will implement a binary search.

Implement the algorithm in Ruby: Day 2 -Bubble sort-

What is bubble sort?

code

Run

Finally