Syntax error Program to define set data structure without using library set class in Python

Program to define set data structure without using library set class in Python

Suppose we want to implement a set data structure with the following methods −

  • Constructor to construct a new instance of a set
  • add(val) to insert integer val into the set
  • exists(val) to check whether val is in the set or not
  • remove(val) to remove the val from the set

So, if we construct a set s, then call s.add(10), s.add(20), s.add(10), s.exists(10), s.remove(10), s.exists(10), s.exists(20), then the output will be

  • for s.add(10) it will insert 10
  • for s.add(20) it will insert 20
  • 10 is already in s, so nothing will happen
  • s.exists(10) will return true as 10 is there
  • Delete 10 by s.remove(10)
  • s.exists(10) will return false because 10 is removed and one element can be there only once
  • s.exists(20) will return true as 20 is present there.

To solve this, we will follow these steps −

  • Define constructor.
  • buckets := an empty map and this will hold a list of data
  • Define a function add() . This will take val
  • if exists(val) is false, then
    • insert val at the end of buckets[val]
  • Define a function exists() . This will take val
  • return true when val is in buckets[val], otherwise false
  • Define a function remove(). This will take val
  • delete buckets[val]

Example

Let us see the following implementation to get better understanding −

from collections import defaultdict
class MySet:
   def __init__(self):
      self.buckets = defaultdict(list)

   def add(self, val):
      if not self.exists(val):
         self.buckets[val].append(val)

   def exists(self, val):
      return val in self.buckets[val]

   def remove(self, val):
      del self.buckets[val]

s = MySet()
s.add(10)
s.add(20)
s.add(10)
print(s.exists(10))
s.remove(10)
print(s.exists(10))
print(s.exists(20))

Input

s = MySet()
s.add(10)
s.add(20)
s.add(10)
s.exists(10)
s.remove(10)
s.exists(10)
s.exists(20)

Output

True
False
True
Updated on: 2021-10-14T09:51:20+05:30

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