chop.rb

# chop.rb
# zastav [@samueltonini]

#1
def chop(v, arr)
  
  return false if arr.empty?
  
  min = 0
  max = arr.length - 1
  mid = (max + 1) / 2
  
  until mid < min
    break if v > arr[mid]
    if v == arr[mid]; return mid; else mid -=1 end
  end
 
  until max < mid
    return false if v > arr[max]
    if v == arr[max]; return max; else max -= 1 end
  end
end 

#2
def chop(v, arr)
  
  return false if arr.empty?
  
  min = 0
  max = arr.length - 1
  mid = (max + 1) / 2
  
  arr[min, mid].reverse_each do |a|
    if v > a
      arr[mid, max].reverse_each do |aa|
        return false if v > aa
        return arr.index(aa) if v == aa
      end
    elsif(v == a) 
      return arr.index(a)      
    end
  end
end

#3
def chop(v, arr)
  
  return false if arr.empty?
  
  min = 0
  max = arr.length - 1
  mid = (max + 1) / 2
  
  (arr.values_at(min..mid)).reverse.detect do |i|
    return arr.index(i) if i == v
    break if v > i
  end
  
  (arr.values_at(mid..max)).reverse.detect do |i|
    return arr.index(i) if i == v
    return false if v > i
  end
end

#4
def chop(v, arr)
  
  return false if arr.empty?
  
  min = -1
  max = arr.length

  while((p=(max-min)/2) != 0)
    if p > 0
      p += min
      max = p if v < arr[p]
      min = p if v > arr[p]
      return p if v == arr[p]
    end
  end
end
 
a = [1,3,2,4,5,8,14,9,7,10,11,24,20,2.3,80,-1,-3,55,66,43,23,15,51,76,13,17,81,98,91,94,18,92,25, 28,34, 41,49].sort 
 
if !(v = chop(76, a)) 
  puts "No such value available in the array."
else
  puts "Value is at index #{v}" # Value is at index 30
end