# Arrays Introduction

strings = ["a", "b", "c", "d"]
# 4x4 = 16 bytes of storage

# push
strings.push("e")

p strings

# pop
strings.pop
strings.pop

p strings

# unshift
strings.unshift("x")

p strings

p "==============Implementation of an Array class=============="

class Arr
    attr_accessor :length, :data

    def initialize
        @length = 0
        @data = {}
    end

    def get(index)
        data[index]
    end

    def push(item)
        data[@length] = item
        @length += 1
    end

    def pop
        last_item = data[@length - 1]
        @data.delete(@length-1)
        @length -= 1
        last_item
    end

    def delete(index)
        item = @data[index]
        shift_items(index)
        item
    end

    def shift_items(index)
        for i in index..(@length-1)
            @data[i] = @data[i+1]            
        end
        @data.delete(@length-1)
        @length -= 1
    end
end

arr = Arr.new
p arr.get(0)
arr.push("Hi")
arr.push("you")
arr.push("are")
arr.push("!")
arr.push("!")
p arr.pop
arr.push("nice")
p arr
p arr.delete(3)
p arr


p "==============Reverse a string=============="


str = "I am the king"

def reverse_str(str)
    return if str == nil || str.length < 2 || str.class != String

    backwards = []
    for i in str.length.downto(0)
        backwards << str[i]
    end
    backwards.join("")
end

p str
p reverse_str(str)

p "==============Merge two sorted arrays=============="

arr1 = [1,2,4,6,8]
arr2 = [3,6,12,45,78]

def merge_sorted_arrays(arr1, arr2)
    arr1_item = arr1[0]
    arr2_item = arr2[0]
    i = 0
    j = 0
    merged_array = []
    
    while (arr1_item || arr2_item)
        if arr2_item.nil? || (arr1_item && arr1_item < arr2_item)
            merged_array.push(arr1_item)
            i += 1
            arr1_item = arr1[i]
        else
            merged_array.push(arr2_item)
            j += 1
            arr2_item = arr2[j]
        end
    end

    merged_array
end

p merge_sorted_arrays(arr1, arr2)